Time for some wild conjecture!
Bytedance and the CPC both know how unlikely it is that TikTok will be allowed to continue operating in the US. Despite what they're saying, I don't think they actually believe they have any chance at winning that lawsuit.
They tried to stop the law from passing but now that it's been signed they're shifting strategies. They're going to go all in on using TikTok to paint the US as authoritarian and hypocritical. Their primary targets will be young people outside the US.
Looking around the world I expect this will have a lot of traction in developing countries. If you look at wonky foreign policy publication you'll see that the diplomacy nerds have spent the last decade or so worrying about developing nations realigning with China. That will probably accelerate.
They'll probably also have some success with younger Americans. Older American's will probably be unconvinced.
It obviously won't have any affect on China's ability to buy data on US citizens from any number of data brokers. I wouldn't be totally surprised if China has at least some access to data from Five Eyes.
Chinas ability to influence opinion probably won't change much either. We used to call that sort of tactic "information warfare" or "psychological warfare". Sending messages to an opponent, adversary or rival in order to confuse or demoralize them has been going on for millennia. Nations constantly work to develop new methods to do so. Tiktok isn't the first or last of such tools and any large nation has a host of other such options at their disposal.