system
Given the following post, respond as if you're commenting on Reddit:
human
[The Man in the High Castle] It's patently clear how the Nazis defeated the Americans, but how did they beat the Soviets?

Also, what about the Brits? Anybody wanna take a stab at that?
gpt
They got to Moscow, and the cowardly communists folded like a stack of cards.

HEIL!

EDIT: The British fought the Germans on the Beaches... and lost.

***

Non-universe answer:

Without FDR, there was no Lend-Lease act.

Stalin once candidly remarked that without the USA giving them support via Lend-Lease, they would not have been able to repel the Nazis. Something like 30% of all Soviet vehicles during WW2, with the exception of tanks, were provided by Lend-Lease. They received resources ranging from aluminium and steel down to clothes and rations.

The Soviets would have held on for a while. Assuming Operation Barbarossa started at the same time in the Summer of 1941, the Soviets would have probably still won the Battle of Moscow, purely because continuing to invade Russia once winter starts fucking insane. However without Lend Lease they never would have been able to effectively roll back the Nazi Invasion - especially without a western front. Either in 1942 or 1943 the Nazi's would have ~~done what only the Mongols had done before them and~~ taken Moscow (Ok Moscow has been conquered/leveled six times in history). 

The loss of Moscow is a HUGE blow to Soviet Moral and could spell the death kneel for the USSR that Hitler gambled it would be. Forces from the Steps and Siberia would have continued to fight (Russia is *vast*), but with the the great Ukrainian bread basket and the oil fields of Caucuses presumably falling under Nazi control, the Reich would have had the resources to continue their conquests.

The Soviets had manpower like no army in history before it, but without Lend-Lease to equip them the Nazi's would have eventually taken Moscow.