The gas tank button on a Chevy Equinox is on the fuel door itself. There is no button or latch to release the door from inside the vehicle. Opening the fuel door is simple: exit the vehicle, push the rear portion of the fuel door inward, and watch it spring open!
Some people worry about theft with a car that doesn’t have an interior latch or release button, so if you’re concerned, your best bet is to purchase a locking gas cap.