He did. They did not call the camps "death camps", but rather Labor Camps. The sign to Auswitz says "Arbeit macht frei" which translates to "Work will make you free". They used slave labor to build many of the camps, work in factories, build roads (many stories of Jewish workers being forced to tear down headstones from Jewish cemeteries and use them to pave roads), and much more. They would work them to death, and then discard them. Often times the only thing that would save an inmate from immediate death was the ability to work, though 99% where given an effective death sentence before they even boarded trains.

Hitler and the Nazi leaderships did use Jews (and other "undesirable" persons) for slave labor. You may be interested in these older threads on the topic:

https://www.reddit.com/r/AskHistorians/comments/2tqf0g/some_holocaust_survivors_were_moved_from_camp_to/co1kc0s/

https://www.reddit.com/r/AskHistorians/comments/3qonin/why_didnt_nazi_germany_kill_all_the_people_in/cwhn9yx/?context=3

and more generally, our FAQ section on the Holocaust and Nazi crimes against humanity:

https://www.reddit.com/r/AskHistorians/wiki/faq/militaryhistory/wwii/nazigermany#wiki_holocaust_and_nazi_crimes_against_humanity