While I have not been there, I can confidently say that they do have elevators, as the law would require them to.
In many cases two story buildings (including some hotels) can get away without them; however, current ADA laws state that if the business (in this case that would be defined as the entire AOA resort) is mixed use or has over a certain number of rooms that elevators are required, even at two story buildings. Many hotels that do not have hotels are pushing the limits and it does depend on when they were originally built and last remodeled.
In addition, Disney strives to make everything accessible, so even if the law didn't require it, they would still install them.