There are currently two methods for tracking how many people abandon (load the first page but do not proceed) your survey.
The easiest way to track abandons is to use a tracking service like Google Analytics. The Bounce Rate provided by Google Analytics will tell you how many people loaded your survey and decided not to proceed.
Check out our Google Analytics Tutorial to learn more.
Clicks in Email Campaign Status Log
If you are using Email Campaigns you can also compute an abandoned statistic from the Status Log. The Send Status field will show Click and the Response Status will remain Not started for all contacts who abandon survey sent out via Email Campaigns. Status Logs are available within email campaigns on both the Contacts step and the Delivery Statistics step by clicking Export Contacts with Send Status.