its pretty easy if you know how it goes.
use the ATGAR turrets and the a-wings/snowspeeder when the shields are off. dont just shot your stupid blaster on it.
ion weapons and orbital strikes are nice aswell.
i would say you have a 40% chance if you know what you have to do.
Is'nt that in a sense unfair then? 40% chance if you know what to do. If you don't, near zero. I know in the film Empire win and I guess Rebels winning in not in continuity but still... should be 50/50 from the start.