I've heard conflicting stories, some saying that the USSR was just too big, and USA lend-lease too much for the Nazis to ever triumph in the East. On the other hand, I've heard that Soviet troops (and Stalin himself) nearly evacuated the city in the battle of Moscow - Surely losing Moscow would mean the end of the war, as the Nazis could just stop there?
I was very surprised that this question isn't already answered in the FAQ. The overwhelming amount of professional historians agree that Germany and the axis at large could not have won WWII. There are a few edge cases that fall more in the realm of speculative fiction (such as Churchill not being Prime Minister, Stalin suffering a stroke in 1941 etc).
The fall of Moscow would almost certainly not have ended the war in Germany's favor. remember that in 1812, Napoleon actually took Moscow after the Russians abandoned it. The retreating Russian troops set the city ablaze and eventually forced the French to retreat the way they had come. Only a tiny fraction of French and allied troops ever returned from that campaign. The memory of this was certainly invoked during the war. So even if Germany had taken Moscow, the Soviet Union would most likely have fought on. Much of the Soviet war industry had already been moved beyond the Ural mountains, far beyond the reach of the German Army or Luftwaffe. Losing Moscow would have been a blow, but not a crippling one, for the Soviet Union's war-making capability (mostly as Moscow served as a logistical hub).
That is beyond even the question whether the Germans would have even been able to successfully attack and capture Moscow. Surely such a strategic goal would have led to a dogged defense by the Soviets, much like Stalingrad, which would have tied up German troops long enough for troops from Siberia to be shifted for a counter-attack, much like it happened in reality.
And of course, the capture of Moscow does nothing to force the British Empire or the US out of the war. The German military was never able to put together a workable plan for the invasion of the British Isles, nor did they have the capacity of shipping to ferry a large enough force across the channel, nor did they have the naval forces necessary to protect such an invasion force, nor did they have air superiority to cover such a force from the air. A German invasion of the British Isles was never a serious possibility (not that the British were necessarily aware of that in 1940).
Finally, there was never even the hint of a plan on how to beat the US or force them into a favorable peace.