You can print a copy of your tax return which will show your married filing jointly status up near the top of the Form 1040. Or you can get a transcript of your tax return from the IRS. TurboTax cannot give you any other verification that you filed a joint return.
https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-get-a-copy-of-a-return-i-filed-this-year-in-turbotax-online/00/25932
You can get a free transcript from the IRS:
https://www.irs.gov/individuals/get-transcript