If your talking about on the metal pontoon itself then no, it wouldn't be gelcoat. Gelcoat is only used of polyester resin in fiberglass composites. If its over metal, its most likely just paint or powder coating with the most likely being the paint.
If theres a hole, you will want to get it welded shut by a good welder since its probably aluminum and thin. If someone attempts to do it that isn't qualified, they will blow a bigger hole than is currently there. They should also be able to smooth out the dented area and get it pretty close to ready for paint. Once the repair is done, you will need to finish sanding and possibly apply some fairing compound to get the blemish to disappear before paint. Then use a good zinc chromate or zinc phosphate primer over the area to allow the paint to stick to the bare metal. Then try to match the current paint. Probably won't look absolutely perfect, but shouldn't be able to tell from 10' if you do it well.
Maybe someone will chime in with a better idea, but thats how I'd go about it.