As you can see, there is a citation for this fact and it was taken from the Elder Scrolls Arena manual which was officially published by Bethesda.

http://elderscrolls.wikia.com/wiki/Tamriel

That is 331,401 square miles larger then Africa. I don't think they could ever make something that big unless they had some randomly generated technology but there would be no point anyway, pvp would be almost non existent unless they had a fast travel system between cities but it would still be to big.

I hope the game will be at least 2 times the size of all of WoW's regions combined including expansions at launch.

It takes you 5+ hours to walk across Skyrim (single player game) from one edge of the map to the other, ESO will have the whole of Tamriel though a lot of it will be locked out to the players at launch so that they have room for expansions and content updates in the future. Cyrodiil the area where the PvP will take place I think is the largest area in the game. All the other areas are probably fairly equal in size at launch.

i won't be big enough. and it will be heavily zoned, instanced, and phased. imo it will be approx. 3/4 the size of vanilla WoW.

How large it is in the lore doesn't really matter much. The games Morrowind, Oblivion and Skyrim are much smaller than they should be according to the lore.

no it doesnt. it takes about 30 min. http://www.youtube.com/watch?v=-YZctTgENLY