Answer:
The Soviet Union would definitely not have been able to defeat Hitler without the help from the West.
Explanation:
The US and Russia surrounded Germany and Hitler's army so there was no where for them to flee. Because of this, they were forced to surrender. If the United States and Russia had not become allies during the time, Germany would have been undefeatable. There most likely would have been a full extermination of anyone other than a blonde haired white person. I believe the day the Soviet Union and the West surrounded Germany was proclaimed V-Day. However, don't quote me on that lol. Its a very interesting topic- I recommend reading more about it.