A few more points:
1. This was in Texas, it was at night, and he was on his own property though not inside his home. They may not have been stealing anything, but they may have been vandalizing his vehicle.
2. If he came out threatening people with the gun, he will have trouble. That gets in the way of a self defense claim even if they were trespassing.
3. Someone in the comments pointed out that a paint ball hit to an unprotected eye can cause serious injury which would allow deadly force in response under Texas law.
4. I am not sure why he shot at the car. Since that may have caused a fatality, that will be an issue.
5. The media can call them kids all they want, but a gang of teenagers is nothing to take lightly if they are truly being aggressive.