From what I've read (including [1]), it is unknown whether Steve Jobs's decision affected the ultimate outcome or even its timing. (I.e., I object to the claim that we know that he would still be alive if he'd agreed to the surgery sooner. It seems that it's possible, but that we can't know definitively.)

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4924574/