Autumn hinted that the player is a CSGO pro and, T1 also hinted that the player has 5 letters to his name and it should be a player from APAC You can narrow it down to Bntet or some other APAC Csgo pro that i don't know of

According to the Youtube Video that T1 Posted (Skip to 1:11) they teased the 5th player, the player has 5 letters so it's probably Bntet

Is it just me or does T1 always get the worst bracket every tournament