How does a star's mass determine its lifespan?

yes it does because A star's life cycle is determined by its mass. The larger its mass, the shorter its life cycle. A star's mass is determined by the amount of matter that is available in its nebula, the giant cloud of gas and dust from which it was born

A star's mass determines its lifespan because the rate at which hydrogen fusion occurs depends on how much pressure the star has on its core ... Both hydrogen and helium rise up through the star and then fall back down. It can last a trillion years.