Answer:
DUI is generally a misdemeanor for a first offense, and therefore max jail time is one year. However, subsequent DUIs are often treated as felonies, and therefore carry a longer max sentence. Additionally, if the DUI is in addition to another charge, such as vehicular manslaughter, the jail time will increase significantly.
The actual amount of time served varies greatly based on the district, the actual facts and circumstances, and the person's history.
First offense DUIs with a clear record and good facts may serve as little as 24 hours, while a person with a bad record and bad facts may do the whole year.