Just some very quick and rough math.
The ground level siteplan has a scale.
Each of the 3 "legs" is approx. 110 by 60 meters = 6600 sq. m. This counts both the clockwise and counter clockwise "buildings".
Each WTC tower was approx 65 meters on a side = 4225 sq. m.
So counting the taper - to level 100 each "leg" is = to the area of one WTC tower. So by level 100 there is already area = to 3 WTC towers.
65% floor area below 100 levels - so approx 5 WTC towers all together.
Now count the 6 level triangular base which is approx 200 meters on a side and the central core - the structure is probably close to 5 1/2 WTC towers in area.
Not gigantic for what they are calling a sky "city" but much larger than one WTC tower. An area equal to 5 1/2 WTC towers would hold what - a few hundred thousand people ?
Also the 15 U/G circular parking levels are a million sq. ft. each. That is near 1/4 of the area of one WTC tower. So just about 4 WTC towers just in parking.
As I said before this structure is more about height than area but it would still be by far the biggest skyscraper ever.
I know - only a vision - but I really like the design and of course the height is fantastic.