If an ex claims that their unemployment has run out and refuses to provide child support what can you do?

my gf's ex claims that his unemployment ran out and is refusing to provide any child support. we know that he is union and has been ping up jobs. what can my gf do about this? does he still have a right to see the children even though he can't support them and provide a financially secure home. Can she provide the courts with doentation that he is an unfit financial supporter? Is there anything she can do to force him to provide any financial support? He is a deadbeat dad to begin with and has already hinted at the idea of not providing any financial support.