My suggestion would be to break the survey into meaningful chunks and present them on different pages so that users dont get overwhelmed by the amount of content and quickly click through. 

That said I would recommend providing some kind of visual indicator which informs users how many questions have been completed and how many are still left.

![enter image description here][2]


  [1]: http://www.zarca.com/Online-Survey-Resource/Survey-Best-Practices/responsible-online-survey-administrator/survey-fatigue.html
  [2]: https://i.sstatic.net/MEMZX.gif