Legal Question in Family Law in California

If you mean does a 14 year old child have significant input on which parent has primary physicial custody in a visitation and custody dispute, then yes. If you are the 14 year old girl who wants to live with her father's creepy friends, then no.

The bottom line answer is "no," not until she is 18. How much input she will have between parents depends on a great number of factors, too numerous to discuss here. If all other factors are equal betweent the two homes, her opinion may be given significant weight by a court, unless her judgment appears clouded or coerced. If one parent is a convicted child pornographer, or something, her opinion will not matter much.