How to get Google Analytics to track progress through a multi-page Drupal Webform?
if the url doesn't change, you can use google's single page applications approach to track:

https://developers.google.com/analytics/devguides/collection/analyticsjs/single-page-applications

You can set a "virtual" url for each page using javascript. Then create a goal funnel in Google Analytics using these virtual url's. You'll probably need to custom write this js to look for specific fields etc to let it know which page it's on.

I think another way is to use custom fields in the call to ga. Not sure if those are available as goals though.