The Japanese had nothing to do with Hitler invading Russia, and that decission lost him the war.It was actually the fault of the Japanese that the Germans lost WWII, not Hitler's. If Hitler had had more unhindered time to invade Britain, he would have been able to succeed in winning the war. Without Britain, The US would not have had a foothold in Europe. If the US had been delayed even a year from entering the war, Hitler would have fully secured his iron grip on the whole of Europe. But we kind of forced the Japanese to attack us...
But to the point of this thread, I think some Americans do have very biased opinions on Russia, but most are neutral like myself. Not paying all that much attention when nothing that affects us is happening.
Even without American involvment (other than our lend/lease aid to Russia & the UK) Germany would have fallen to the Soviet Union by 1946, '47 at the latest.
Hitlers decission to invade Russia once he saw that Sealion wasn't panning out in September of '40 was probably the single worst decision he made during the war. But he wanted his people to love and support him and it just wouldn't do to have a huge standing army sitting around doing nothing, so he set his sights on Russia, whose Slavic people he hated with a vengance and whose land and resources he had long lusted after.
The British were a nuisance to Hitler. He was fighting them because they had declared war on him, and naturally he wanted to win that war. But if the British had offered him peace he would have taken it. Britain offered very little in the way of lebensraum and resources. Additionally, Hitler considered the British people to be of Aryan stock, far different from the untermensch of Russia.
Without a Western Front Hitler would have been able to give the Russians a little bit more of a fight, but it ultimately would have come down to a battle of attrition (much as it did) and the Russians simply had more men to throw into the fight.
At best Hitler could (maybe) have taken Britain, but he never would have taken Russia. This is assuming that the American Army Air Force wasn't steadily bombing the shit out of German manufacturing, which it was and which would have continued to have done under any but these completly hypothetical circumstances.