Yes, TurboTax Deluxe Online includes Form 8615.
If you have already started your 2019 tax return in TurboTax Online, you should be able to complete it. You can e-file it until October 31. If you have not yet started your return, it's too late to start a new 2019 tax return in TurboTax Online now. You would have to use the CD/Download TurboTax software.
I looked for Form 8615 but didn't find it. I'm already at the review stage of my online return. Where do I find Form 8615 if I've already started my 2019 return? Not obvious.
Form 8615 is used in the "child's" tax return to calculate the kiddie tax. Are you subject to kiddie tax, or are you preparing a tax return for someone who is subject to kiddie tax? (You could be as old as 23 and still be a "child" subject to kiddie tax if you were a full-time student.)
In TurboTax Online you don't see the actual forms until you print the tax return or create a PDF. If you need to enter the kiddie tax information, type "Form 8615" (without the quotes) in the Search box, then click the link that says "Jump to Form 8615." When you enter the necessary information, TurboTax will fill out the form.