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I'm not quite sure what Facebook Autofill function you're referring but we have FitForm Integration.
This basically captures user information from their Facebook Profile once they login using the FB Login button on the form.
If in case you're looking for saving the form and continue later, here's a guide: https://www.jotform.com/help/227-How-to-Enable-Auto-Fill-Feature
If you have further questions, let us know.