All of the clubs participate in the Revenue Sharing program that basically pools money like ticket sales and the like. Therefore, the operating expenses (read: players' salaries) are covered by the NFL Revenue program.
However, any and all marketing / sales efforts locally creates revenue streams that get kept by the Owner. For example, signage around Paul Brown and ads sold during their Bengals Weekly with Marvin Lewis TV show. Obviously, larger markets can create WAY more local dollars in this fashion that pad the Owners' bottom-line. However, the beauty is they can't use those monies to increase payroll, therefore, the playing field stays fairly level.