Just to reiterate the other comments, "had" is wrong because you included "in his lifetime" to contextualise it -- this implies the period of time known as his

Just to reiterate the other comments, "had" is wrong because you included "in his lifetime" to contextualise it -- this implies the period of time known as his "lifetime" is in the past, which is wrong because he is still alive, and so "had" is incorrect. If one had said "Bill Gates had donated over $x [before he was 55]" it would be fine.