If I’m going to court for Class A misdemeanor theft but have a prior felony for DUI, what type of punishment will I get?

The best answer is "it depends."  Generically-- the max sentence for a Class A misdemeanor is one year in county jail.  Even it you have already been sentenced in a felony DUI case, the prosecutor can make an offer of something less than jail time.  Whether you will get this type of offer will depend on multiple factors:

1.  The rest of your criminal history.  If your history looks bad, then expect the prosecutor to give you a higher plea offer.

2.  The attitude of the prosecutor.  Some prosecutors are very "gung ho," while others really don't care-- they just want to move the case along.  If you get a "move the case along" prosecutor, you will get a better recommendation.

3.  Special issues with the jurisdiction.  Some counties have had a lot of difficulty with jail over crowding.  If the jail where you could be sentenced is not very crowded, then the prosecutor would offer jail time.  If the prosecutor has to choose between keeping misdemeanor versus felonies in jail, you have a shot at not getting a jail time recommendation.

4.  Strength of your case.  Believe it or not, the person handling your case initially may not be the prosecutor in the courtroom.  The one in the courtroom is usually more experienced and will notice issues in your case before the intake grunt.  As such, if the court prosecutor sees issues, they will offer you a better deal to get rid of the case.

I'm sorry this is not an exact answer, but sentencing in the state system is not exact or calculated like it is in the federal system.  If you want to get a more exact feel of what will happen in court in your jurisdiction, consult with an attorney that routinely handles cases in this jurisdiction.  They can give you a more specific feel for the issues affecting the county where you are charged and the nature of the prosecutors that will be reviewing your case.