Question

How does gravity affect the life cycle of stars?

Answer 1

Gravity is a function of mass. It is the enormous gravitational influences that causes nuclear fusion within stars.

Explanation:

If you accept, as you must, that gravity is the causal factor of nuclear fusion in all stars then you can infer by extension that the larger the star, the greater the mass; the greater the mass, the greater the gravity; the greater the gravity, the faster the rate of nuclear fusion. The faster a star "burns" the hydrogen available to it, the shorter its life.