Typically, if you're banned from chat, you will be banned for one day. If you were banned yesterday, the channel operator who banned you hasn't come back online yet to unban you (and, probably, no one else who witnessed the ban have either). For a first offense, this should be the case with you. A second offense will result in a longer ban and so on.
However, depending on the severity of the rule breaks, you may have been banned for longer. I can't speak with certainty about what you have done to be banned from chat so I can neither confirm nor deny what your ban duration will be, but in some instances this is the case. The operator who banned you will unban you based on the duration they deemed appropriate.