Yes, it is possible to bet on PUBG games. You can find some sportsbooks that offer wagers on PUBG tournaments. However, PUBG has become a shadow of its initial popularity. The Esport scene is not that big and doesn’t spotlight anymore apart from the mobile version.
The legal age for gambling can vary depending on the laws of where you live. Pretty much every sportsbook website will have a minimum age limit requirement of 18 years, if not 21.