Hmmm, interesting point, by all of the definitions here Alonso is a pay driver. The deal between Santan and Ferrari for sponsorship defines that Alonso be at the wheel and that Santan will cover his wages as long as he is as well as supplying extra capital to the team. So Alonso gets no payment from Ferari other than the money provided by a sponsor...
ALL drivers bring money to the team through sponsorship etc, the real question is whether a driver would be in that seat without that money? But again, even in the top teams, there are few drivers who would be there without the added sponsorship they bring in just for being at the wheel. I don't think it is possibl to have a definition of a Pay Driver in the current F1. In the old days some people were there on merit and got paid, others paid to sit in the seat, the split was definable and obvious. Today with the corporate money that is needed to run a team I don't think most of the drivers would be there if they didn't at least bring something to the team financially.