Is it true that the immigration has a quota when they issue a work permit?

Shey, I am confused by your question. The work permit is issued by the labor bureau in the city where your employer is located at. The normal process is that your employer gets the work permit and invitation letter from duly authorized unit for you. Then you take both to apply for the Z type from Chinese embassy in your country. Getting your Z type, you should come in, apply for the employment certificate and then change the Z into resident permit. All these things should be done within 30 days. Usually, if you have your Z type and employment certificate, you will get the long-term resident permit for sure.