Aquaseal is good stuff, as is Goop (both similar urethane glues) but any PVC patch kit should make a good strong fusion weld. Even the cheap kits that are sold for PVC pool repairs, all same stuff.
I'll throw in with the choir and question the surface prep, because any contamination could be a problem. Best to clean the area with isopropyl alcohol and paper towels, work your way out and treat it like you were doing surgery on yourself--you want it sterile and clean. Then rough it up, abrade with CLEAN fresh sandpaper, and not the cheap stuff that leaves grit behind. Something good like 3M Tri-M-Ite. Follow by cleaning again, to remove any dust or debris.
Then apply the solvent and patch (which is also fresh and clean one hopes) and clamp or weight until it has cured. It should be fused into the PVC and it will stay that way. If it isn't, maybe the inflatable isn't really PVC, or maybe it has another problem, like contamination causing it to fail.