I think even OTL China will win in the end no matter what.
with Oil Embargo:
If everything is OTL until December 1941, the addition of the flying Tigers to the region in December 1941 is going to increase the attrition on the Japanese going forward even if they dont attack the USA, the oil embargo is on, attitional costs are high. Japan can't sustain this for long.
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without Oil Emargo:
If for some reason IndoChina is Free French they likely would resist a Japanese incursion into IndoChina in the OTL September 1940 time frame and that line of supply is still open (OR the Japanese just don't invade to avoid USA emargos). OTL the Japanese failed to cut this from the Chinese side so they had to cut it from the French side.
So at this point Japan is in a war with China they can't win and can't sustain, the Chinese are still receiving outside supply via a rail line from IndoChina (more than OTL).
So even without USA war against Japan (and even if the Japanese can still buy oil from ther USA) the Japanese will be eventually forced to ask for peace terms or just pull back to Manchuria anyway just because they can't sustain the long term costs.
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However there is no way for China to win before 1942 by themselves than I can see.