I'm sorry, i misunderstood the question.
Here, and i think mostly everywhere, the HOUSEHOLD income is what is used to determine eligibility. That means that the primary household ("custodial parent" is often used, or, in cases of joint custody, the parent with whom the child lives 51% or more of the time. ) is used to determine a child's eligibility for public programs. So, in a situation where the mother is the primary parent, IF she is living with someone (be it boyfriend or husband) then YES, that persons income is used, because assistance goes by HOUSEHOLD income.
In court situations, the stepparent's income can generally NOT be used to calculate child support.