I'm not saying there have never been any in crescent lake (it's florida - I'm sure there have been and will be again), I'm just saying in my three years of driving on that water, I have never seen a single gator. And while I always hear my co-workers mentioning snakes they see (and once, there was an otter everyone talked about for a week!), I've not heard anyone ever mention a gator aside from the ones spotted in the years before I came there. Again, I know it's not impossible for them to be there, but I think they prefer the little canals and retention ponds in the more quiet areas of Y&B and the boardwalk (which DEFINITELY have gator sightings quite frequently).
Tl;dr - gators in crescent lake are of course possible but they are few and far between.