Can I put a limit on RSVP on a form after I've sent out the form?

Can I put a limit on RSVP on a form after I've sent out the form? Will it effect the link associated with the form? 

I assume you were referring to the submission count limit? If so, you can change that by following this guide https://www.jotform.com/help/137-How-to-Limit-Submissions-in-a-Form.

Let us know if you have any questions or if you need further assistance.