To go nerdily pseudoquantative I would expect roughly a exposure * quality * originality impact. If something introduces a new trope or context and it is widely

To go nerdily pseudoquantative I would expect roughly a exposure * quality * originality impact. If something introduces a new trope or context and it is widely watched it ends up echoing itself with imitators and callbacks unless discredited. If it is novel but is niche or panned it will introduce the idea to a few and may rarely get snuck in as an obscure reference or inspiration. (See the B-movie influences on major film-makers.) One random example for theory crafting is how Avatar has become infamous for how forgettable a movie it is from lack of originality and poor plot. Forgetability aside, if a myth or concept is already widely believed or known there isn't as much change it can introduce and worse, it risks becoming seen as boring. There are all sorts of messy cross-correlative details too like big budget works taking fewer risks and being less original owing to the stakes.