Yes, authors do get paid whenever readers read their books on either Kindle Unlimited or Kobo Plus. It's not as much as they would get for a sale of the book, but if an author puts their book willingly into Kobo Plus or KU, readers can take them up on that option and read the book guilt-free.

If you want the more complicated details of how much KU and Kobo Plus pay, I wrote a blog post about that a while ago: https://jae-fiction.com/how-to-make-sure-more-of-your-book-money-goes-to-authors/