We had a substantial leak in our water heater, to the point where the insulation was soaked around the tank. We had that fixed by a plumber but now the pilot light will not stay lit. it will light, and seconds after turning the heat back to on it will go out. It has now been over 24 hours since leak was fixed. Could the leak have damaged something that is replaceable? Does it just need to completely dry out? Our plumber says we need a whole new water heater.. . Any suggestions

Typically when a pilot will not stay lit the thermocouple needs to be replaced. I suggest you get a plumber to disassemble the burner assembly and clean off the burner and replace the thermocouple and brush the pilot orifice. Also check to see if the vent is obstructed. I do not suggest you work on the gas because of the danger involved.