Admission was free to the cathedral itself, though you needed to pay to visit the roof.
Of course it was a draw to Paris in general. It's hard to measure its impact, since the cathedral fire coincides with COVID, but Paris tourism has nearly reached pre-pandemic levels and remains the most-visited city in the world.
I don't honestly believe it would be a net economic benefit to put a Starbucks there. But more to the point, the whole thing is there just because people like to look at it. That's all the "productivity" it needs.
