Pact had advantage in numbers. Also in this TL Warsaw Pact was a bit more royal to USSR(ASB, yeah), and they had luck on their own side
Is this based on a book or movie? If so, this is the wrong forum.
If not-
IOTL the various Pact countries, with the possible exception of the DDR, were restive beyond words. It is likely that Soviet Army formations would have been engaged by at least some elements of the Polish military, very possibly the Czechs and Hungarians as well. The Soviet military was also at a low ebb that hadn't been seen is prior to the Winter War. This is the version of the Soviet military that was quite literally unable to get most of its tanks to start, lacked fuel to train pilots, had ammo stocks that were mouse eaten and warships that were vin virtual sinking condition tied up to the quay.
On the other hand, the NATO powers were, arguably, at their very peak. The U.S. military had not suffered from the successive "peace dividends" that greatly reduced force leaves, the British Army was at a high point, as was the Heer, the French military was also nearing its post war max effectiveness.
Until Moscow pulled the nuclear button out of the holster the Soviets would have gotten rolled.