l know the feeling of fireball pressure forever. my best advice, is when he spams instant air fireball, try to break his rhythm with a gunshot, he'll take longer to recover because he either chooses to lay there or tech roll, and you use that time to get in on them. my thought is, why try to duck and move when you can knock him out of the air with a straight gunshot. the trade is worth the ability to get in before he recovers.
I beat a guy at next level who did this to me on rooftop metropolis stage.. I managed to edge it out.. but i think the key is trying to show him you don't give a shit about his instant air fireball because once you get in, cyborg has a hard time getting you off him, and he gives up too much damage off the grapple hook and gives harley an opportunity to still mix him up. this is only based off of the one cyborg i played at next level, and the online cyborgs i play. I hope this helps in some way.