If a water heater is leaking from somewhere other than the usual pipes sticking out of it then the tank has rusted through.
A water heater does not possess an intake or "autofill" valve that opens and closes as needed. The tank is sealed and cannot "overflow".
The only legitimate place for water to pour from a water heater onto the floor is the pressure/temperature relief valve, visible on the outside. And this outflow should not be happening all the time.
