You can try to misidentify Caitlyn Jenner by her former identity, but Siri isn’t going to let you get away with it. While the iPhone voice search app will recognize the name Bruce Jenner, it won’t repeat it back to you — at least, in most cases.
Instead, Siri changes the name Bruce to Caitlyn, thanks to Wolfram Alpha, the knowledge engine the app searches for many of its answers. If you ask Bruce Jenner’s height, it replies “Caitlin Jenner is 6’2″ tall.” If you ask for Bruce’s full name, Siri answers, “Caitlin Jenner’s full name is Caitlyn Jenner.”
The app will even give Jenner’s correct gender, female. Siri isn’t perfect, though. Some information is served via Wikipedia, which still calls Jenner by her former name.