Not easily as their terms are private, but you can tell it's not a huge slice. Fairly well every phone and all manner of other devices uses an ARM but I'm googling their royalty revenues at $1.3 billion dollars annually. So that's not much per device shipped. Stuff you hear suggests maybe they get 1% on the sale price of a CPU. Note that's the CPU price, not the phone. The CPU in a phone might cost e.g. $20 so they maybe get 20 cents off that. I expect they have other revenues from design assistance and support etc but those costs would apply to a RISC-V device also.