"...can Alpha Centauri be seen from Florida?"
Just barely. The southernmost point in CONUS is Key West, FL, at 24d 30m N Lat. Theoretically, the furthest south you can see from there is is (90 - Lat) = Dec -65d 30m. Alpha Cen is at declination -60d 52'.
It pops up a few degrees over the southern horizon for a few minutes each day.
