Open a file upon submission of your form

The confirmation text is only displayed to the user after the form is submitted. You could include a link to the PDF in the confirmation text message so they only see the link if they submit the form.

That doesn't secure the PDF itself from them giving the URL of the PDF to a friend, but Gravity Forms isn't in the business of content protection so that isn't something we could prevent. But it would provide a simple solution for offering a PDF download behind a form submission.

Include a PDF that contains submitted data? I'm a little confused. Do you mean you want a PDF to be created from the data submitted in the form itself? If that is what you mean, Gravity Forms has nothing to do with PDF creation.

If you want to make a PDF available for the user to download after submitting a form, you would edit the Confirmation message for that form and add a link to whatever PDF you want them to download in the Confirmation text. You would have to add an actual HTML link to the confirmation text.

Example:

<a href="http://mydomain.com/mypdf.pdf">Download PDF</a>

You would have to upload it somewhere such as your Media Library and then get the URL to it and create a link using HTML in the Confirmation text.

Gravity Forms itself does not have a PDF creation feature. It's certainly possible to do so, however that would be a customization and outside the scope of the Gravity Forms feature set itself.