I would like to store a SharePoint survey in a folder of a document library. How do I do this? Whenever I create a survey it stays separate from my document library and cannot be dropped into a file structure like a document can be.
I don't think you can. A survey is a special type of list, and a document library is another special type of list, as is most everything in SharePoint. (A calendar is a list, a tasks list is a list, etc.)
Everything that you see when you go to Site Contents is essentially a list.
You can't store an entire list inside another list.