How does a streaming service determine how much (incremental) revenue is generated by a show/movie?

Does anyone know the methods that a streaming service (Netflix, HBO Max, etc.) use to determine the revenue generated by specific content, as in a television series or a movie?

For the sake of this question I am assuming this is "original content" for the streaming service, not some sort of licensing arrangement.

I figure breaking down income from traditional TV shows on primetime networks is relatively straightforward - ad revenue, merchandise, product placement, DVDs. And traditional box office movies can work the same way (just replacing ad revenue with ticket sales).

But for a show like Stranger Things on Netflix, what measures are they using to determine how much to budget each season? I understand there is still merchandise sales and product placement and even cooperative advertisements (not sure if this is profit or just shared expense, doesn't matter), but what about ~actually~ tying in their main source of revenue - monthly subscriptions - to a specific show?

You can look at the number of total streams, unique streams, etc., but what measure do they use to tie how much in additional subscription revenue is attributed to a given show/movie? And then therefore how much to budget for a given piece of original content?

I assume these streaming giants have fairly sophisticated ways to determine this, but I have no idea. Maybe there's some sort of widely accepted ratio of streams:subcriptions that they use, idk.