One zone in FFXI is equal to one Aetheryte camp and the surrounding area.

So all you'd have to do is count the number of zones that were available at FFXI's release in Japan (I don't know this statistic)

And compare it to the number of camp sites available to us at release (22, plus the 3 city states, and the 6-7 dungeons accessible at the time of release)

Do that, and you'd have your answer.

The reason XIV feels smaller is that each city state is closer to the other. Windurst and San'doria had about 7 zones seperating them. Limsa and Gridania have about 5.

The trip to Jeuno in FFXI can take well over 45 minutes on foot (chocobo's have a time limit of 30 minutes). The trip from La Noscea to Uldah is 15-20 minutes, and half of it is by boat. The rest is a road that cuts right through the massive Thanalan map.

There's also the issue of the stagnancy of the maps. Eastern Thanalan isn't very different looking from Western Thanalan. If you took screenshots of either spot and compared, you'd be hard pressed to spot a difference. That has a psychological effect. If the area around you isn't changing much, you must not be going anywhere, so you subconsciously think the area is smaller than it actually is.