He should consult with an experienced criminal defense attorney. Most, like us, offer free consultations. Also, I would advise not paying the restitution until after he has spoken with an attorney.
It may be possible to resolve the case with a "Compromise of Misdemeanor" under RCW 10.22.010. It will require that he pays the restitution and that the injured party agrees to the resolution. Some stores, such as Wal-Mart have a strict company policy that they will not agree to a Compromise of Misdemeanor and will require that the matter be resolved through a criminal prosecution.
However, there are other alternatives such as Pretrial Diversion Agreements that allow the matter to be continued on conditions such as fines, restitution, community service and sometimes a consumer awareness class. If all conditions are met, the charges are dismissed after a 1-2 year period.
These are not the only options to avoid conviction but during your consultation, an attorney can advise you of additional options depending on the facts of the case and his history.
It's good that you want to help your friend, but please leave legal advice to the legal professionals.
There are usually other options for first-time offenders, which will allow the case to ultimately get dismissed. However, whether those options are available depends on the facts of the case and the prosecutor assigned to his case. Your friend should speak to an attorney about his options. If he cannot hire his own attorney, he should apply for a public defender.