"In 2003, Shin Jung-hwan was fined 5 million won (about USD $4,600) for gambling. He was fined double that in 2005. Later he was caught on video tape gambling in the Philippines. That was enough to spark his arrest when he returned to Korea, for which in 2011 he was given an 8-month prison sentence"

I'm pretty sure that, at worst, Seungri will be fined.

Source of this is KBS, by the way: http://news.kbs.co.kr/news/view.do?ncd=4272014

So, let's get this straight: He did in fact admit to most of the gambling charges that were handed to him earlier by police. Gambling itself is illegal for Korean citizens in (and outside of) Korea - except at one place: Kangwon Land, a casino and resort company located in the Gangwon Province. This means Seungri did commit a criminal act by gambling overseas, since the Korean criminal law applies to Korean citizen throughout the world. Like it or not, but that's how the Korean law works.