According to The New Yorker, those restaurants are supported by an underground network of employment agencies, immigrant hostels and asylum attorneys. Journalist Lauren Hilgers describes a system in which Chinese-run bus companies drop workers off and then take them home.
Some workers take their salaries and pay the smugglers that got them into the United States and also send money back home to family.
“There are only three jobs a Chinese immigrant can get without papers,” a woman from Beijing looking for work said. “You can work at a massage parlor, you can work doing nails, or you can work in a restaurant.” Most of the jobs at the New York agencies are out of state. Workers must be ready within hours of getting the call to come to work to hop on the bus.
Prices to be smuggled from China to the US can vary. One person said she paid $12,000, but another paid $70,000.
You can read about how many are smuggled and their life once they get to this country in The New Yorker.