Can I add a payment link on an invoice that I create or add the payment link to one of the pdf templates that is available for download

I  see that you have opened a separate thread regarding your concern and one of my colleagues have already replied to it — https://www.jotform.com/answers/1617804

However, just to explain it further, you can add a link to the email sent to your respondents every time they successfully submitted your form.

Or, if you want to include a link to the PDF copy of the submission of your form, you can add the link to the form first using the Text field

And, make the Text field shown on the PDF submission. — How-to-show-headers-or-text-for-contracts-terms-agreements-in-the-PDF-format-of-a-submission