In my long experience with the game, I have never seen the Axis side win. However, if you play by the rules, instead of somebodys twisted version of it, you would have bid for powers, and sides dont win, only individual powers. Quite often you will see people make stupid bids to play powers that no longer have a chance of winning (such as Germany) that skew the results. Or, you may decide you dont like bidding and go by the historical levels. Even so, if you add up the allied side, vrs the Axis side, you will see way more games in the allied favour, because they can drive out and get them.
China needs 2.
CW needs 19.
France needs 1.
Germany needs 10.
Italy needs 0.
Japan needs 5.
USA needs 17
USSR/CC needs 13
Or you can go for Automatic Victory: Control Berlin, Canberra, Chungking, Delhi, London, Moscow, Paris, Pretoria, Rome, Taihoku, & Tokyo. and your side wins automatically. The other side gets zero. You get your objectives and the enemy/neutral objectives closest to your capital.
The options you use will skew the game as well. Some options favour others. If you use bidding, then play balance is automatic. But if you dont, you are making it easier/harder for different sides/countries to win. I would say that in the dozen or so games I have played to 1945, the CW is usually the winner, with the Italians, or Russians in second. Germany rarely does well, and usually has less then 10 objectives left. Japan can do okay, but suffers easily from auto victory as they only control the fate of Taihoku and Tokyo (and perhaps Chungking).
If you use bidding, then their is a lot less cooperation amongst the allies, and maybe even infighting to the axis credit. If you dont use any victory at all, Germany/Italy/Japan are hard to conquer. If you use historical levels, then the allies are one big happy family and can usually dole out victory so that everyone on their side wins equally.