This depends on whose memory you are talking about. For leader-types, academics and historians looking to study someone with massive charisma and ambition, it's Jobs they are going to remember. Videos of speeches and interviews will be preserved, and where Jobs and Gates are side by side it's clear that Jobs is the one with the presence.

For everyone else including the general public, it'll probably still be Gates, but Jobs certainly won't be forgotten, if for no other reason than his involvement in Pixar. Pixar's original string of hits (Toy Story{, 2}, A Bug's Life, Finding Nemo, etc) are definitely going to survive in public consciousness longer than 50 years. The narrative of Pixar itself will probably survive that long as well.