Is it possible to use answers from one form to prepopulate another form's questions on submission?

Yes. Please check the solution described on this user guides:

#1 https://www.jotform.com/help/351-How-to-Automatically-Pass-Form-Data-to-Another-Form

#2 https://www.jotform.com/help/286-How-to-Pass-Field-Value-to-Another-Field

Hope this help. Let us know if you need more assistance.