Tire tracks, igniters (gas or lighter fluid), a dropped lighter, or just raising patrol strength in an area. Arsonists aren't usually one and done guys, we had some asshole set 8 fires before he was arrested last year.
To answer your question about the match. I don't think a match would do it. I haven't really be following the case closely but here is my best guess to how it started. Since this fire is in Florida and Florida usually has between 80 and 98 percent RH, the arsonist would need more that a cigarette or book of matches. In more arid places like Montana you can just lean out your car window with a cigarette lighter and set fire. In this case, he'd need an accelerate like gas or something, which can be easy to trace. So long as nature doesn't mess things up.
Accelerates burn quickly and leave fumes, but you have to get there pretty quickly. Also if the guy used wood or debris to start the fire that will probably still be around as well, fires get started with fine fuels which burn quickly but not completely. There are many ways in which they can catch the guy, but unfortunately none are easy. The best bet is to raise patrols in the area and just wait. Unless of course they've found a lead I'm unaware of. Like an eye witness or something.