Can the Allies win this game, given that Russia is falling?
This is a tough one. But it appears to indicate that under certain circumstances, the U.S. and Britain together could have won, even if Russia is falling. Your game illustrates how.

1) Secure North Africa, and with it, the road to the Middle East and India.

2) Using India as a base, reclaim China, Indochina, and some of the Pacific Islands from Japan. This is something you accomplished in the game that the Allies failed to achieve in real life.

Doing a rough count: the U.S. starts with 36 IPCS, and Britain with 30. You've added 3 or so in Africa, and perhaps 11 in "greater China" for a total of about 80. The Axis have 29 for the original Germany minus North Africa, will soon get 24 for Russia, and have about 14 left for Japan, a total of 67. That's more than the 57 they started with, so they've "come up." 

One advantage for you is that you've "sluffed" your weakest player and country (Russia), and "consolidated." Also, Japan is "half gone." The end game is an alliance between America, Britain, (Japan and China), the latter two controlled by the former two, versus Germany and Russia (the latter under German occupation). That will win most games of Allies and Axis. Probably the "real life" version as well.

One idea: Ship at least American infantry and tanks across the Pacific, where the Japanese navy is in its death throes, to China, rather than across the Atlantic (where there are eight German submarines. Have them conquer the remaining Japanese Pacific islands along the way to reduce Japan's income, before heading for China, and ultimately Siberian Russia (you want to reduce the Axis to 29 for Germany, 24 for Russia and 8 for Japan, or 61). Use British land forces for harassing the Germans in France, Norway, and the Middle East/Southern Russia.