Neoprene is full of small bubbles that contain air (other gases are also used) which give you insulation. So yes – all this air trapped inside neoprene will give you some buoyancy. The thicker the neoprene the more added buoyancy. BUT! This is still NOWHERE near the floatation you get from wearing a life vest. Wetsuit buoyancy is like a little added bonus and not something to rely on when things get sketchy. If you get caught in a rip you need to use some common sense to get your ass out of the “situation”.
Wetsuit, life vest or nothing…principle when caught in the rip is the same: “Never swim (paddle) against the rip!” You wouldn’t try to swim upriver to save yourself would you? You will loose energy and accomplish nothing. Instead – swim perpendicular to the rip and you will eventually get out of it. Once you are out you can swim towards the shore.