Firms based in China make sales to America almost exclusively through goods export, which were worth $506bn last year. American companies make their sales to China both through exports and throught their subsidiaries there, which together delivered abut $450-500bn in revenue. Again, there is not much of a gap. American firms' aggregate market share in China, of 6%, is almost double Chinese firms' share in America, based on the sales of all listed firms. Are American firms shut out of some sectors in China, clearly yes, however, Chinese firms can make a similar complaint. The market share of all foreign firms in Silicon Valley's software and internet activities, and on Wall Street, is probably below 20%. America's national-security rules, thickets of regulation, lobbying culture and political climate make it inconceivable that a Chinese firm could play a big role in the internet or in finance there. In a tit-for-tar war in which China punish American firm's Chinese subsidiaries very easily could result in the opposite of what USA wants.
*) the Economist 30th June 2018