How exactly did Gambol die from the Jokers knife?
The Joker has his blade in Gambol’s mouth, threatening to cut his cheeks. And presumably he does, off camera. There is a belief among some fans that you can’t die from having your cheek slashed, but it is possible; laceration of the face was listed as a cause of death in the infamous Black Dahlia murder. The shock and blood loss could cause death. It’s also possible that the Joker got carried away and went beyond cutting Gambol’s cheeks. Since the murder happened off camera, we don’t know.