Thanks for asking.
Unfortunately, you can't get a demo from X Theme to Pro Theme as both uses different templating engine. Pro Theme does not comes with demo import function, instead it has got Design Cloud.
However, there's a way that can be used provided one is having X Theme license. So, in X Theme users can setup and design their website by importing the demo content like App and then users have the option of converting to Pro Theme. For more information, please take a look at following article.