No you do not have to pay child support for a child that is not yours unless you adopted that child (and then they would be yours).
Michael is in San Jose, California and can be reached at 408-295-4232 or at firstname.lastname@example.org. Consultation fees, rates and retainers vary based on need and ability to pay.
I agree. Unless you have adopted this child you have no financial responsiblity.
Note that should you and the mother not stay together you may also have a right to visitaiton even if you don't have a responsiblity for payment. I do not practice in California but CA and my state (Connecticut) are often on similar grounds when it comes to family law. You will need to speak with a practicing family attorney about that.
This not legal advice which can only be given after a full disclosure and discussion regarding your particular situation. Any answer or comment by the attorney des not create an attorney client relationship and is not protected by privelege.