With the right approach, both sites can bring good profits. You need to choose the one that you like more and develop it.
But starting to make these two businesses grow is not that an easy thing. My suggestion is just focus on a single business first and for me I would love to choose a gambling site, this is one of the reason why bitcoin's price is increasing. The demand of bitcoins to the gamblers is increasingly very fast and once you built your own gambling site perfect running and has plenty of player then go next with a dating site.