There are a total of 168 RNC members, and the contest could go for multiple rounds of balloting until one candidates gets the magic number of 85 for a majority. There is no forcible cutoff of lower candidates, but their voters tend to fall away -- and the candidates themselves drop out -- once the initial votes are cast and it becomes clear which candidates cannot win. (Steele won the 2009 race on the sixth ballot, out of a field of five candidates.)
The question then becomes how those uncommitted voters will split on the first round -- it is believed that many of them could go to Steele, in gratitude for the party's successes in the past cycle -- and whether the votes for the lower candidates will unify behind any single candidate in successive rounds. But as it stands, of course, Priebus remains the person to beat.
The other candidates all bring something to the table. Priebus's Democratic-leaning state went deep red in the 2010 elections. Wagner headed up Sen. Roy Blunt's (R-MO) landslide win in an open-seat race. Anuzis has headed up the GOP in a Dem-leaning state, where the GOP also made big gains this past fall, and he previously ran for chair in 2009. And Cino is backed by many top GOP insiders including Speaker John Boehner (R-OH) and former Vice President Dick Cheney.