There seem to be some differing numbers of 5.20 and 5.60 gallons (19.7 and 21.2 liters, respectively).
There isn't a difference in capacity between countries is there? Searching through posts for Eighth Gen fuel ranges, some members from Spain, Australia, Germany, and UK have filled 19.7 to 20.4 liters (5.2 to 5.39 gallons). And yet, the manual I have and Honda North America's website for the VFR800F notes a 5.2 gallon fuel capacity. Some reviews on the 2014/15 mention 5.6 gallons.
On my 2015, haven't ran to dry but most I've filled is 4.738 and that's 15 or so miles after the E light coming on at 216 miles on the trip odometer. Haha, it's been bothering me and I'm just really curious.