Comprehensive coverage in Georgia, like in most all states, covers your vehicle for things "other then collision" such as fire, weather, vandalism, floods and theft. When a car is stolen and not recovered the insurance company will settle for the actual cash value of the vehicle before it was stolen.
The Georgia Insurance Commissioner site discusses how if your car it a total loss, which a stolen vehicle is since it taken from you, your full coverage through your insurance company will pay you what the car was worth based on its current book value (or ACV).
If you owe more money then the actual cash value of the vehicle, you will be responsible for the difference of what the vehicle's ACV settlement is and the balance of your car loan. If you have GAP insurance, it would pay the difference in what you owe and the ACV paid out so that you are not left with an outstanding loan on the vehicle.
Without GAP insurance, if you owe more than the what the comprehensive settlement is on the stolen vehicle, than you will be responsible for paying on the remainder of the loan to the lien holder.