This is not one of the forms that can be completed in TurboTax Business. You won't be able to file a Gift Tax Return with TurboTax. A Gift Tax return should be filed separately from your personal income tax return as it has no effect on taxation at the individual level.
The IRS provides Form 709 and Instructions here:
IRS
Gift Tax
IRS
Gift Tax FAQs
IRS Form 709 - US Gift Tax
Return
