A civil lawsuit is unlike a criminal case where the number of jurors varies depending on the type of crime being charged. For a civil case, in our great state of Indiana, you will be allowed 6 jurors. You and the other side can agree to fewer if you find it strategic to do so. Once either of you has requested that the case be tried before a jury (make that request right away in a lawsuit) the court will then proceed to appoint 6 members who live in the county to sit in on the trial. There may also be appointment of alternate jurors, usually 2. The alternate jurors are there to sit in if another juror gets sick or otherwise must leave the trial.
Specifically, the Indiana court rule pertaining to jurors says "In all civil cases, the jury shall consist of six (6) persons, unless the parties agree to a lesser number of jurors before the jury is selected." and "The number of alternate jurors shall be governed by Trial Rule 47(B)."
Good luck.