How to interest a researcher in a topic (social science)? I have created a thesis related to the objective utility and evaluation of art.  It is based on many years of personal experience in the arts, as well as many years of study into the philosophy of aesthetics.

I believe this thesis could be tested quantitatively by a trained social scientist, and that the results would hold both scientific and commercial interest.

Is there any possibility an academic researcher (either a grad student or a professor) might take on research on a thesis he or she didn't originate?  If so, what would be the best route to connect with that person, and how would the idea need to be presented (and/or what preliminary work would need to be completed first)?
It would be a fairly difficult process.

Firstly, you would need to convince someone that you aren't a crank and are worth listening to. Once they listen to you, you'll have to convince them that your work is of such import that they should stop working on their current projects—you can assume that everyone is at full capacity already, and that adding your project to their task will decrease their involvement elsewhere—to research on your topic. Most academics are academically motivated by the love of their field, the possibility of getting one or more respected publications, and the prospect of getting a grant, not necessarily in that order. You can only appeal to the first two, and likely only the first one. That's not a very strong argument.

You also stated in your opening question "I believe this thesis could be tested quantitatively by a trained social scientist...". The implication here is that you are not such an individual. (I'm not speaking of degrees, I'm simply speaking in terms of experience in performing academic-level research and analytics.) In that case, are you certain your research thus far is valid? Your entire thesis could be based on faulty statistics, poor sampling, a misunderstanding of some fundamental concept, etc.

Long story short, you have an uphill battle ahead of you.