Yes. A properly served subpaena requires the witness to appear.
A bench warrant can be issued for the witness and it's 'good cause' to continue the hearing until the witness is found. It's up to the prosecutor as to how the case proceeds from there ...... but....
Be careful. It's a separate felony if you are contacting the witness (or having a third party contact them) and encouraging the witness not to appear. Intimidating a witness is serious.
The witness should appear and testify truthfully.