Pausing or closing a survey will block data collection by preventing access to any surveys that have been sent.
Pausing a survey will simply put it on hold--invitations scheduled will still be sent, but it won't be possible to access the survey from them.
Closing a survey will delete any scheduled invitations.
You can un-pause or re-open a survey at anytime.
To pause or close a survey:
Once the survey has launched, go to Setup, then Advanced:
Go to Survey Name and Status. Under Status, choose either Pause or Close. Click Update when you're finished: