As of Pega 7.4, a survey object is a special kind of case type. 

The harness is a UI component that can be specialized to the work class of the survey case type. 

Therefore, you could specialize a harness for the Work class of the survey and end up with the same result as you are seeking.  As a harness is a UI element, you can only add UI elements to the harness.  We cannot, to the best of my knowledge, add a case type to a harness, but rather, it is the other way around.

So, if you have requirements for how the survey should be presented, then specialize the harness for the work type created when you create the survey from the survey landing page (I believe that, OOTB, the TabbedScreenFlow7 harness is used to display a survey).  The survey has all the same attributes of any other case type.  When you create a survey in a flow using the survey shape, you are essential doing the same thing that you would by adding a Create Case shape.

Hope this helps!