What happen if the hull of submarine ruptured?

All modern submarines are "dual hull" constructed. What you see on the surface is the outer hull, or "superstructure". The inner hull, where the main systems and crew are, is protected by the outer hull.

Damage severity of either the outer or inner hulls depends on the boat's depth at the time. If deep enough, it doesn't take much damage to the hull, as sea pressure will be virtually unstoppable, even with the quick-reaction damage control skills of a submarine crew.

However, if sea pressure isn't a factor and the flooding can be controlled, then it's possible to survive such a casualty. Again, it depends on the severity of the hull breach, and the depth at the time.

Several modern submarines (my old boat included) have survived underwater collisions which produced severe damage.