Can you attach a pdf file to an efiled return. Specifically for the statements required on the 3115

No, attachments cannot be attached to an e-filed tax return when using TurboTax.

If you need to include an attachment to your tax return you will have to print and mail the return.

See this TurboTax support FAQ for how to print a tax return using the online editions - https://ttlc.intuit.com/turbotax-support/en-us/help-article/printers-printing/print-mail-return-turbotax-online/L5bwuqXGy_US_en_US?uid=lwxzz3du

You cannot attach a PDF to an e-file return and particularly not a 3115 (which (a) typically requires its own separate statement and (b) requires that a separate copy be printed and mailed to the IRS).