The winners, the people who provide the best set of predictions based on an analysis of a database of millions of text questions, will get jobs at Facebook.
Actually, it looks like the winners will just get interviews at Facebook.
I think Kaggle is a very interesting site and company, but I think it's a stretch say they hold "data science" competitions. Most of their contest are extremely limited in scope to applying machine learning to pre-sanitized data sets. This really covers only a small part of what practicing data scientists do.