You may not always have the email addresses of everyone you wish to invite to the survey. In that case use an invitation via paper. Put a link to the survey in this invitation so that they can still fill out the survey online.
You can either use 1 generic URL that’s the same for all recipients. In that case the survey will be anonymous (unless you ask for contact details), and you won’t be able to keep track of who’s already responded and who hasn’t.
Or you can combine the paper invitations with contacts so that each recipient receives a unique URL that can be used only once. When they start filling out the survey the contact status will change to “responded” so that you know who’s filled out the survey and who hasn’t. Additionally you can import other meta-data along with your contacts for future reporting purposes.