Correct, on the right is Antony "Tony" Habersack Jannus, pilot of the first scheduled passenger service using heavier-than-air aircraft. On the left is his brother, Roger Weightman Jannus. The man in the middle could just be a fan who wanted his picture taken with them. The Jannus brothers traveled the country giving air tours in many cities after their airboat line in St. Pete / Tampa. I can rule out the man in the middle as being Percival Elliot Fansler, the drivng force behind the St.Pete-Tampa Airboat Line. It's also not Abram C. Pheil, their first passenger and former mayor of St. Pete. He might be an investor. After St. Pete / Tampa, the Tony Jannus gave flying tours at Cedar Point, Ohio. See www.tampapix.com/jannus.htm for more info.

This appears to be a Benoist Type XIV flying boat, used in 1914 on one of the first commercial US air services, from Tampa to St. Petersburg. The aircraft was designed, built and operated by the Jannus brothers, Roger and Tony. Maybe they are two of the people in picture? Both would die in the First World War, bringing an end to the Benoist company.

Man on the right looks like he could be Tony Jannus, the first airline pilot.