No tax credits are not 'subsidies'.  Yes, tax credits are based on labour expenditures, but the people employed on these shows pay taxes on those earnings.  And there are other expenses paid  by film/tv production which aren't eligible for tax credits - things like equipment rentals, vehicle rentals, office & stage rentals, catering, accommodation for out-of-town cast/crew, etc.  The businesses which deal directly with film production employ people (who pay taxes) and also pay corporate taxes.     
When you look at the big picture, film/tv production is a net economic benefit to the province.