Yes - if you are still in your return, you can click on My Account at the top of your screen and click Save & Sign Out. This will save all of your progress. In addition, TurboTax Online automatically saves as you work on your return.
Please see TurboTaxRobertaT's response to the question, "Can I Save My Progress?", below:
https://ttlc.intuit.com/replies/5389088