Can a testical hernia kill you?

Technically, yes..: I'm assuming you mean a groin or inguinal hernia, which allows fat or intestinal tissue to drop into the scrotum. If bowel becomes incarcerated (stuck) in a hernia and becomes strangulated (tissue dies) it could lead to a patient's death, but very rarely. Of course, in extreme situations an elective repair of a hernia could lead to death, such as by heart attack or blood clot. Unlikely. Good luck.

Unlikely.: If a hernia twists on itself or gets pinched between tissue and cuts off its blood supply it can die and become infected. This infection can cause death if not treated. Fortunately a hernia cut off from blood supply generally causes fairly severe pain that brings you to medical attention.

Possible: If an inguinal hernia becomes stuck, or incarcerated in the scrotum, it can lead to gangrene and death if left untreated. The hernia lump is usually hard and very painful when this occurs. If that happens, don't delay - seek medical attention urgently.