Possibly Sourced from Open Doors
All the numbers in the quote seem very similar to the numbers produced by Open Doors, a venture sponsored by the US State Department to collect statistics about US students overseas, and international students in the US.
That's up from about 200 during the depths of the pandemic.
211, according to Open Doors.
[T]here were over 11,000 Americans studying in China in 2019
11,639 according to the same interactive as above.
[T]here are nearly 300,000 Chinese students in the United States
289,526, according to a different page on the same site.
But the one number I couldn't verify on the site was the "800 currently in China" statistic.
The most recent data is from the 2021/2022 school year - so my guess is that the source of the quote is a government official or Open Doors employee with access to data that has not yet been finalized or published. If so, we'll be able to confirm this number in a year or two when the data is put online.
800 Actually Seems Reasonable
The data we do have shows that China has become less attractive in recent years:
While the total number of US students abroad increased from basically none in 2020/2021 to about half of the pre-pandemic total in 2021/2022, the number of US students in China decreased over the same time period, going from 382 to 211.
I would speculate that some combination of strict COVID lockdowns, the post-COVID Chinese economic slowdown, and increasing US / Chinese tensions have made China significantly less attractive to US students, but we'd need some kind of polling to back that up.
Context
China represented about 3% of US overseas students prior to the pandemic - the majority of US students were going to Europe if they were going abroad.
China doesn't have as many high ranking universities as the West - US News and World Report puts 3 of the top 50 global universities in China, compared to 13 in Europe (and 7 between Canada and Australia, where English is an official language).
And 2 of China's 3 high ranking universities are in Hong Kong, which has been in the news for unpleasant reasons in recent years.
Given that, I'm not too surprised that US student's interest in Chinese Universities waned as the Chinese economy cooled, tensions between China and the West rose, and the PRC cracked down on internal dissent; China wasn't a major destination for US students in the first place.