It is easier for me to believe that a movie specifically about the Russians winning WW2 simply would not get financed due to low probability of earning a decent ROI due to American/English audiences not wanting to pay to watch it.
I was also taught in US history AP class in high school that a significant, if not necessary, element of winning WW2 was the Russians tying up the Germans on the eastern front, and it was stressed that the Russians suffered the most casualties by far.
The Soviets along with some remaining Polish forces also won the battle of Berlin (which caused Hitler to commit suicide), having pushed back the German army all the way back from the gates of Moscow to the gates of Berlin. The Third Reich, left with no "leader" and no capital and no significant territory neither in the east nor in the west really had no option other than total capitulation or total defeat. The capitulation happened a week later. The Western Front and the Eastern Front in the end had about the same amount of German causalities and captures.
Anyway, the Soviets did a little more than "just" tying up Germans on the Eastern Front.
Furthermore, I've read [2] that historiography on the Eastern Front was quite poor, even from the Soviet perspective, until Stalin's death. From [2], page 12: > Soviet military works written before 1958 were highly politicized and focused heavily on the positive role of Stalin in every aspect of war. Correspondingly, operational and tactical detail was lacking.
Though Cold War politics did play a role.
[1] https://en.wikipedia.org/wiki/Category:Films_about_the_Battl... [2] PDF WARNING: https://community.apan.org/cfs-file/__key/docpreview-s/00-00...
Russia didn't win WWII, given that they didn't fight Japan in any meaningful way.