Unknown. Itauma is faster and harder hitting. If he catches Kabayel coming in, it will be devestating for Kabayel. But Itauma's chin and stamina are unknown. We don't know how Itauma will handle being hit by a proper heavyweight with good skill and power. IMO Kabayel will be cautious early and then break Itauma down and stop him late. That being said, if Itauama ends up showing he has a good chin, his ceiling is way higher than Kabayel. Itauma is quicker handed, harder hitting and has the added advantage of being left handed. He is also over a decade younger.
I'm not even confident Itauma beats Whyte. Kabayel far too proven and experienced for Itauma. Kabayel's bodywork is unlike anything Itauma has ever seen. Kabayel KO.