The issue is that Calcutta and egypt are still insanely hard to hold with good axis play. On top of that, the German + Minors can get a doom stack set up very quick, and force russia out of leningrad.
This gives the axis easy boost with spain. On top of all that, Germany does not need to take moscow, it just needs to take and hold stalingrad. This should not be a problem since russia is forced to turtle Moscow.
The only way russia seems to have a chance is if he ignores China & Japan and focuses 100% on G.
When the allies are landing in normandy, but still cant feasibly take paris, even with germany losing its entire airforce, its really gg.