Either Lewis by decision or by mid to late TKO depending on how ugly ruiz makes it and how aggressive Lewis gets
Ruiz would do his ugly octopus thing and Lewis would hold his head down and hit him with brutal uppercuts. Lewis was a master of the "hit-and-hold uppercut". Sometimes it was done more quickly and subtly, other times more blatant. Either way, Ruiz loses badly.
Lewis uses his strength to push Ruiz off and land the right and and uppercuts. Lewis by mid rounds ko.