I have started using the Survey App in Sharepoint for company staff surveys. We have a large mobile workforce that we want to engage and it would be great to be able to use Powerapps to surface a survey from the Sharepoint Survey app onto PowerApps. As far as I can see the only link to Sharepoint right now is from a standard or custom list view.
This is now possible today if you build a custom list for your survey, and/or if you used some other list type. In the later case, you should also be able to connect to it using the same method for document libraries (see below link for details on that).
I might need you to clarify what you mean by survey lists if you think this is not completed. I believe the older 'survey' list type from SharePoint 2010 may no longer be available on SharePoint Online.
Two other modern options:
I might also suggest using either "Microsoft Forms" for basic surveys, or a 3rd Party like "Survey Monkey" for very complex or branched surveys, as we have the ability to connect to that data, or to repurpose the data on submission using Microsoft Flow.