New Post: redirect survey for after clicking finish

I haven't tested any of this with a survey list, but with custom lists these techniques work.

List forms can be redirected after submission by adding a Source parameter to the URL. So if you are linking to the survey from somewhere (and not having users click the "New" button on the survey's overview page), modify the link to be something like this: <a href="http://yoursite/lists/yoursurvey/newform.aspx?Source=http://yoursite/pages/thank-you.aspx">Respond to the Survey</a> where "thank-you.aspx" is your custom thank you page.

Or you can create a new view of the survey using the web UI (no need for SharePoint Designer) and add a content editor web part at the top of the view with your thank you message.

Or you can add some Javascript to the default survey list page that uses SPServices GetListItems to see if the user has responded to the survey, and if so, either redirects the user to a thank you page or displays a thank you message in a content editor web part on the survey overview page.

Or you can do the same using a data view web part instead of SPServices if you prefer server-side code.