Yep, my aunt died at 86; after surviving cancer at least twice she kept chugging along until she basically just dropped dead one day without warning. They found she had cancers throughout her body which is probably what killed her in some way, but some people are just able to keep going and fighting them off for a long time.
There are several kinds of pancreatic cancer, and it’s kind of misleading that they get lumped together. The most common one, adenocarcinoma, is almost always very rapidly fatal. But the kind Steve Jobs had, neuroendocrine, is slow and treatable if you’re not an “alternative health” idiot. It’s likely that’s what she has.