I’d keep cat and baby chickens separate, at least until they are adults. I’ve heard a determined hungry cat can kill an adult standard chicken, but I suspect it’s rare. Standards are as big as a cat and cats naturally go after, and are designed to go after small creatures like mice. Baby chickens though are little yummy nuggets that don’t fly very far, so err on the side of caution. That said, I’ve never had a cat get a chicken or chick. I even have a huge TNR’d boy now who doesn’t bother with the chickens. He doesn’t have access to the half-grown ones though! My suggestion is keep separate, bring the cat indoors (if you can), and monitor/introduce when the chickens are as big as the cat.