How does twitter rank replies on a tweet?

Imagine a celebrity makes a tweet. It gets tens of thousands of replies, hearts, and retweets.

A few of those replies will be ranking on top of the thread. What does it take to reach the top?

You can retweet, like or reply to those replies too. The replies with the most or strongest signals get to the top. It's not a power order though. Since Twitter effed up the chronological timeline of the tweets and prioritizes influencers, nothing is in order.

Timing can also play a role. If you're quick enough and you're able to reply to a tweet early and let's say your reply is remarkable in some way (e.g. funny, smart), the chances are that it will gain momentum by itself.

You need likes and retweets to your reply, the more and faster - the better. Plus your accounts needs to have some authority. But as HoNeyBird said twitter a bit messed up lately so you never really know.