How much tax does KFC have to pay for invoicing?

Not fixed. I'll give you some reference.

According to the business tax regulations, the business tax rate of the catering industry is 5%, plus 7% of the business tax for education (5% for counties and 3% for towns), business tax 1%, and income tax 1%-5%. Usually the urban area is about 10%.

The catering industry is a "hard" tax, and there is no tax without invoicing. Therefore, most provinces and autonomous regions are promoting award-winning invoices in the catering industry, allowing consumers to urge restaurants to pay taxes.