what is the ban message?
if the message say something about the period of time then it is a temp ban, otherwise it is a perma ban and won't expire
With it being what OP called "evasion" he will not be coming back. Evasion is a perma ban.
He can wait a while and PM one of the admins and ask nicely to get unbanned. But as far as time right now I would say forever unless an admin changes it.
evasion is perma ban only after you get the 30 day ban and get caught ban evading, then you get a perma ban.
if is your first ban and you are caught ban evading, your ban will be doubled