To answer your question directly, for the most part, Jewish forced labor was oriented toward tasks that were useful for the economy or the war effort, and instances where prisoners were deliberately worked to death or tortured by excessive physical labor were less common. The use of Jewish forced labor in Germany and other countries was a constant balancing act between the economic needs of the state and the war economy and the goal of racial extermination of the Jews. These countries balanced these issues in different ways, and the relationship between forced labor and genocide evolved significantly over time. Back in the early days of Holocaust studies, Jewish forced labor was commonly discussed within the framework of "extermination through labor", but more recent work has revealed that this paradigm is overly simplistic and that there are a lot of nuances to the connection between forced labor and the Holocaust.

Forced labor for Jews and other concentration camp inmates in Germany obviously preceded the onset of the Holocaust by several years. Within weeks of coming to power, the Nazis began setting up the first concentration camps and other types of prisons and detention facilities. Prisoners in these camps (both Jews and non-Jews) were generally forced to work in some capacity, generally on projects of local economic interest, e.g. construction or cleaning the streets in urban areas or agriculture in more rural areas. It should be noted that this labor was separate from the Reich Labor Service (Reichsarbeitsdienst), which was a system of voluntary (later compulsory) labor service for non-Jewish Germans rather than a true forced labor system. The aforementioned balancing act was uncomplicated at this stage because there was no Final Solution to prepare for, so economic gain was really the only motivation.

After the war began, the character of forced labor in Germany changed as the country's economy shifted into its wartime mode. There were a variety of different situations where Jewish forced labor was used during the war. Prisoners who were in concentration camps continued to be used as labor within those camps and their subcamps, while purpose-built forced labor camps (Zwangsarbeitslager) were established across occupied Europe. In some cases, the forced labor camps were used to provide labor to a specific company or industry (such as Auschwitz III-Monowitz, whose prisoners worked for IG Farben), while others were simply "hubs" for forced laborers in a particular era. In cases where the labor was used by a particular company, the SS Main Economic and Administrative Office (SS-WVHA) would often charge the company a fee for the use of the laborers (e.g. the prisoners sent to IG Farben from Monowitz cost the company 3 RM per day).

The types of labor that Jews performed in Germany and occupied Europe varied according to local needs; in more industrialized areas like western Germany and Silesia, prisoners were often used in factories, while in mountainous areas they were used for mining, and so forth. Prisoners in camps and ghettos closer to the front were often used on military construction projects, which was dangerous and difficult work. However, in all of these cases, the prisoners were doing work that was productive and useful to the war effort.

It should be noted that there was internal debate within the Nazi leadership about the course of Jewish forced labor and its relation to the coming Final Solution. Himmler, Heydrich, and the SS argued that they should eschew the use of Jewish labor in order to speed up the extermination of the Jewish population, while Göring and others on the economic side of the Nazi leadership argued for the continued use of Jewish labor as a replacement for the manpower that had been lost due to the mobilization of millions of German men of working age. Göring's argument that the potential of Jewish labor was too valuable to simply throw away won out, in large part, and Jewish forced laborers (along with other forced laborers) remained an important part of the German war economy. In the end, those Jews who were able to continue working productively or possessed specialized professional or technical skills tended to survive much longer than those who were not of working age/fitness, since the skilled workers were either assigned to work outside of the concentration camps or were selected for work rather than gassing if they were deported to the extermination camps. In most cases, the practical, economic needs overrode racial ideology, which enabled some people to survive.

This question also played out in other countries which were aligned with Nazi Germany. In Hungary, Romania, and Bulgaria, Jews were expelled from the military under antisemitic laws that were passed in the late 1930s and early 1940s, and their compulsory military service was replaced with mandatory labor service. In those countries, Jewish men were organized into labor battalions which operated either within their home cities (generally intended for older and younger men and men with children), performing relatively menial tasks like clearing snow from the streets, while others were deployed to more remote locations to perform construction work or other intensive physical labor (generally these were younger men without children). These labor battalions weren't intended to be part of the killing process, since none of those countries had concrete plans to kill Jews at that point. After the Axis invasion of the Soviet Union began, the paths of forced labor in Hungary and Romania diverged sharply. The Hungarian government decided that it would attach its labor battalions to its armed forces and send them to the front. Jewish laborers were assigned some of the worst and most dangerous tasks, including laying and clearing minefields and clearing barbed wire. Many people were killed as a result of these dangerous jobs. After the Hungarian forces were completely routed by the Red Army in early 1943, many surviving Jewish laborers were either killed by the Soviets in battle or executed by the retreating Hungarian forces. In this sense, forced labor became part of the Final Solution in Hungary, and more than 30,000 Hungarian Jewish laborers died.

In Romania, by contrast, Jewish laborers were never sent to the front. The Romanian government began to develop its own plans to eliminate the Jews in Romania by deporting them "to the East", i.e. to Transnistria and eventually into Nazi-occupied Ukraine. They were also separately negotiating with the Germans for the deportation of Jews living within Romania proper to Belzec, which was slated to begin in the fall of 1942. During this time, the Romanian government saw forced labor as a "temporary solution" to the "Jewish question", an intermediate phase before the "permanent solution" could be achieved, rather than as a part of the extermination process. Ultimately, Romania chose not to go along with the Nazi deportation plans, meaning that the Jews living in Romania proper had been spared their lives, although forced labor and other antisemitic measures would continue on until the end of the war. In any case, the Romanians weren't trying to kill the forced laborers, just to extract economic utility from them until it came time to kill them.

Now obviously you can look at this, particularly with respect to Germany, and say that the conditions in the camps meant the deaths of the forced laborers were inevitable and that this demonstrates the intent for extermination through labor. However, the behind-the-scenes jockeying for position among the Nazi leaders demonstrates that there wasn't really a cohesive policy as such; the deaths were simply the result of prisoners being overworked while living in unsanitary conditions with inadequate food. Of course there were cases where concentration camp guards forced prisoners to do pointless labor or strenuous physical exercises simply as a means of torture, but the actual forced labor system was designed to be economically productive in the time until the Final Solution was completed rather than a method of extermination in and of itself.

It's worth noting that forced labor for Soviet prisoners of war followed a similar arc. The Germans actually weren't all that interested in using them as forced laborers (at least not within the Reich) until after the Battle of Moscow and the failure of Barbarossa to deliver the knockout blow to the Soviet Union. The Germans were more or less content to just let them die until the spring of 1942, when Hitler reversed course and declared that Soviet prisoners should be used for forced labor, perhaps realizing that Germany was facing the prospect of total war and that its reserves of manpower for labor were totally insufficient for such a war.