it will have an impact, but we shouldn't encourage people to follow them blindly. And then most celebrities or well known people shill for projects or coins that aren't that great. They promote it because they get paid for it. They don't know jack shit about the project they are promoting. Though the affect is short term it might cause a long term damage. But yeah, at least more people will get to know about crypto currencies when they talk about it.
We literally had exactly that with Elon Musk. Dude loved bitcoin and dogecoin and promoted them to death, he kept on tweeting about it, and even though I do not use twitter I still managed to see his tweets because it was basically right there. So at the end of the day, we are talking about something that already happened. Which is why I personally hope that we get to see a lot more of good tweets if that is the only thing we are going to get, but if we are going to see bad tweets as well then I do not want the good ones neither. Famous people talking about crypto is not as good as imagined, it is something that is quite difficult to overcome when they change their mind or even simply just stop talking about it.