Performance=Airbus A319 max takeoff weight is 75.5tons or 166500 pounds\nAirbus empty weight is 40.1 tons, or 88400 pounds\nMax fuel load is about 23 tons or 51722 pounds

So when the aircraft is at Max fuel (7835gall=51722 pounds) the max payload for the plane is:
166500 - 88400 - 51722=27378 pounds or aprox. 12 tons