A bit on this topic, I have to say I have NEVER seen any Chinese immigrants. In my games as the US, Brazil, USCA, I have never seen any (or at least so few I never saw them, and I check frequently to manage immigration) immigrants of any of the cultures that inhabit China.
I tried giving China every commerce and industrial tech to boost their base needs to try and force shortages and thus migrations, but it had no effect. I even loaded up as China, and found that the AI was taxing the low class 100% (they had put in a state capitalist party that was forcing the AI to spend thousands on reforms, and even with max taxes and tarrifs should have been losing money yet had over 100K in the bank), and that they were getting basically 0% of their basic needs (and those were national culture pops), and yet the population in China was continuing to massively grow. When I loaded as China, I was seeing several pops emigrating to the US, but when I loaded the game at the same point as the US, they were not recieving any immigrants from China during the same period.
Obviously, the AI is getting some kind of massive economic cheats, and either I do not understand something about immigration or there is something screwy going on. RIP 1.4