You pay first because if TT let you have all of it before you pay, how would they enforce payment----too many people would just re-copy it and mail it without paying.
You can see your 1040, but that's all. In order to see the rest you pay first.
PREVIEW 1040
https://ttlc.intuit.com/questions/1901539-how-do-i-preview-my-turbotax-online-return-before-filing
Click on Tax Tools on the left side of the screen. Click on Tools. Click on View Tax Summary. Click on Preview my 1040 on the left side of the screen.
https://ttlc.intuit.com/community/printing/help/can-i-print-a-copy-of-my-turbotax-online-return-befo...
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**