Yes a person can die from a gunshot to the stomach.
Getting shot anywhere is never good but you can die from getting shot in the stomach if you have internal bleeding.
Some people who get shot in the stomach may not even know they have internal bleeding so you always need prompt medical attention to prevent death or serious injury.
If you get shot in the leg then it's less serious than getting shot in the stomach, head, heart etc but even infections can occur when you get shot in the leg.
I've heard of a few cases where a few people have died from getting shot in the stomach.