Ok I did a little searching. She might get some of the $336 to the publisher/songwriter, but only if she is credited as a writer. Not every song is written by the artist. There doesn't seem to be anything in that breakdown that goes to the artist specifically. The bulk of the money is going to the copyright owner, who is often the record company, and seems to be who owns her songs. It seems like whatever she gets paid would be up to whatever contract she signed with them.

This pdf file explains that a typical major label artist might make 18% of the $4077 per day.

https://www.manatt.com/Manatt/media/Media/PDF/US-Streaming-Royalties-Explained.pdf

If she makes $266 a day from onlyfans, she has to be making around 8% of the $3,239 the record company is getting daily for it to be less than onlyfans.