When Lisa Stevens, Paizo owner and CEO, was asked "...you're saying that it's your belief that the Pathfinder brand has a higher sales volume than the D&D brand"
"At this time in history, that is what I have been told by people in the hobby distribution trade, the book trade, and other avenues that both games sell their products into. If you talk to the various retailers, it is a mixed bag, with one telling you one thing and another a different story. But when you talk to the folks who sell those retailers the product that they sell, then you get a clearer picture.
And I am just talking table-top RPG business. I am not talking about board games or card games or video games or whatnot. Just books and digital copies of those books for use in playing a table-top RPG.
Read it here, as well as the rest of the discussion.