1. We make money from companies via recruiting fees. In this scenario, our goal would be to present listings that we make money from via "sponsored links" a la Google search. As we grow our pool of job-seekers, we'd concurrently be able to expand the number of companies we have recruiting agreements with, thus making our implicit incentive to be biased towards a small number of companies weaker and weaker. If we got a significant portion of all job-seekers using our service, we'd probably be able to introduce a standardized recruiting agreement that companies could sign onto online in a self-serve fashion, minimizing our need to do "on the ground" sales.
2. If that approach doesn't work, we'd hope to offer services to job-seekers that they're willing to pay for, such as resume reviews, interview coaching, and the like. There's also the possibility that we could come to some agreement with seekers for a (very small) percentage of their signing bonus/salary at a new job that we help them find. Obviously we have to provide excellent service to earn this, but that's what we aim for!