Yi Ti and the other lands to the east of Westeros/Essos appear to be modelled after Japanese/Chinese cultures from the writings. It's hard to provide an exact quote from the books about how you come to this impression but in The World of Ice and Fire there is a chapter named The Bones and Beyond: Yi Ti which gives some description of the place and it's history. From my reading of the chapter I certainly got the impression it was based on an Oriental style culture.
The cities of Yi Ti are far-famed as well, for no other land can boast so many. If Lomas Longstrider can be believed, none of the cities of the west can compare to those of Yi Ti in size and splendor. "Even their ruins put ours to shame," the Longstrider said...and ruins are everywhere in Yi Ti. In his Jade Compendium, Colloquo Votar—the best source available in Westeros on the lands of the Jade Sea—wrote that beneath every YiTish city, three older cities lie buried.
Over the centuries, the capital of the Golden Empire has moved here and there and back again a score of times, as rival warlords contended and dynasties rose and fell. The grey emperors, indigo emperors, and pearl-white emperors ruled from Yin on the shores of the Jade Sea, first and most glorious of the YiTish cities, but the scarlet emperors raised up a new city in the heart of the jungle and named it Si Qo the Glorious (long fallen and overgrown, its glory lives now only in legend), whilst the purple emperors preferred Tiqui, the many-towered city in the western hills, and the maroon emperors kept their martial court in Jinqi, the better to guard the frontiers of the empire against reavers from the Shadow Lands.
The World of Ice and Fire, The Bones and Beyond: Yi Ti
Whilst I can't find an exact quote of George R. R. Martin admitting to basing these Eastern regions off of our own the following certainly implies that he has done and it doesn't quote him denying it.
Since it's a hot-button topic, I commented to George about how some were bothered by what they see as "cultural appropriation" in the novels, citing in particular his presentation of Yi Ti with its obvious influences from Imperial China. George first addressed the term "cultural appropriation" by saying that "it's bullshit." He went on to discuss his own heritage, an American mutt with bits of Italian, German, Irish, etc. in his background, so does that mean he has special rights or ability to write about Italian culture? Of course not. He said that history belongs to everybody, and that the accident of blood or birth doesn't give one any special rights. As to Yi Ti, he discussed it in terms of fleshing the eastern regions out. I noted that I thought that it was quite fascinating, and I think (someone correct me) I pointed out how Yi Ti is this civilization older than that of the Seven Kingdoms, seemingly grander and more advanced, so it wasn't as if it was a negative "appropriation."
So Spake Martin, Srockholm and Archipelacon Report
On a few related side notes, it's worth mentioning that George does not like to make 1 to 1 comparisons to anything. So whilst something may be heavily inspired by something else it won't be directly comparable; he'll add in other influences, his own twist and of course a hint of fantasy.
Well, yes and no. I have drawn on a great many influences for these books. I do use incidents from history, yes, although I try not to do a straight one-for-one transposition of fact into fiction. I prefer to mix and match, and to add in some imaginative elements as well.
So Spake Martin, Historical Influences
George has also mentioned that he's only really included these lands to the East for world building purposes and are not that important to the story he is telling.
There's been an interesting discussion on our forum concerning "orientalism" as it's expressed in your work, and one question it's led to among readers is whether you've ever considered a foreign point of view characters in Essos, to give a different window into events there.
No, this story is about Westeros. Those other lands are important only as they reflect on Westeros.
So Spake Martin, Westeros.org Interview
Lastly, I think it is worth pointing out that George, in 2007 at least, had never been to China and most of his historical influences came from European history.
Hadrian's Wall, of course, I think was the inspiration for the Wall. I've never been to China so I've never had a chance to see their Great Wall but I have been to Scotland and I have walked along what remains of Hadrian's Wall and that was actually an inspiring experience.
So Spake Martin, Second Life Appearance