Jeez, the Allies are letting Japan get away with India and are still winning games?
Maybe the Japanese player isn’t doing his job of moving enough forces into Africa and Europe.
One tactic that worked well in AA50 was for Germany to either build a factory in France or a fleet in the Baltic, and somehow contrive a way for a German carrier to be put/sent into the Med to help Italy out. After a few turns Italy could afford CVs of its own, so Italian CVs were built with extra German fighters on it to stack with the German fleet off Gibraltar. This usually worked pretty good holding off the Brits and US for a few turns. THEN, after Japan has taken India, they send a few loaded CVs, BB, and planes up through the Suez to join up with the rest of the Axis to hold the Med. Usually Japan at this point can finish taking over Moscow from the Nazis and initiates the final attacks to destroy the Western fleets in the Atlantic.
If you can force the Allies into spending their $$$ on ships and planes for a combined Axis fleet battle that can be reinforced easily around Italy, you can essentially split the Western Allies forces since they can only attack with one power a turn, versus you defending with three. This way they also never can come up with the $ for transports much less ground troops for invading the mainland. If Italy can hold in the Med, pretty much the rest of the Axis are safe as well since it would take a lot of time for the Allies to manuever their ships towards Germany. If you hold the Allies at Gibraltar they can’t even send troops to Africa, which will eventually leave Britain as a rump state as Italy takes all of it.