Newspaper articles may give leads on this, though you will need to plow through quite a bit of opinion and unsubstantiated claims. If you are near a large library, databases to try would include Proquest Newspapers in public libraries, and Lexis Nexis Academic or Factiva in academic libraries. Virtually all public universities and colleges - and many private ones - allow you to search these expensive databases if you come onto campus. In Lexis Nexis Academic, the search: arts w/5 economic benefits gets 209 hits. Possibly a better search is: arts w/5 economic benefits and studies (50 hits), or arts w/5 economic benefits and statistics (21 hits).
A useful free source is USA.gov, which includes many state as well as federal web sites, reports, proposals, studies, hearings, etc. The search: "funding for the arts" statistics gets 90 hits; "funding for the arts" "economic benefits" gets 62; "funding for the arts" "return on investment" gets 18; "funding for the arts" roi gets 2; "arts funding" roi gets 12, etc. Note that usa.gov, with its Google search engine, handles phrases with "on", "of", etc., that some commercial databases sometimes still have trouble with. For example, Business Source Complete (available on campus at large academic and some large public libraries) gets 14 hits for the search: arts and funding and return and investment. But the search: arts and "return on investment" does get 102 hits. A better search seems to be: arts and funding and "return on investment" and "economic benefits", which gets 101 hits if you "Select a field" TX-All text (Business Source defaults to titles, author names, subjects and abstracts)
Jim Miller - firstname.lastname@example.org