For example, the subject of an interview is an interviewee.
So, I was wondering what the subject of a survey might be.
despite the fact that most of us are inundated with surveys and they most likely use such a word in their communication, all I can think of is:
(all the obvious constructions just don't sound like they are used despite their 'correctness'.)
Since someone who conducts and survey is a surveyor then someone or something being surveyed is the surveyed.
Similarly to how the object of a tormentor is the tormented.
Simply subject of survey. Or you can use surveyed object. There does not seem to be any one-word synonym for it. If you don't consider survivor as one :)
The subject of survey, in a sense, is surveyor, but the best suited word or the subject I would use if I made a survey is pollster.