He posts frequently for his fans to enjoy photos, so it's no surprise that he's been steadily gaining followers. He joined the platform not too long ago and hit 1 million in a few days, so it seems he's probably well on his way to 3 million and perhaps soon even past 5 million like G-Dragon has.  

If you don't follow him yet, you can do so here @choi_seung_hyun_tttop!

Tip: anree