Can my ex get child support lowered if he has another child?

My ex has remarried, has a stepchild, and has another child due any day now. He has also received a pay increase since the order went into effect 2 years ago. I was working 2 part times jobs (1 about 4 hours a week minimum wage, the other about 33 hours a week), 5 months ago I received a full time position and quit the minimum wage job. I haven't received a raise in over 2 years and won't be getting one anytime soon (raise freeze) so the only benefit to the full time job is being about to make the same amount of money at one job and being able to be home more more with my child. My ex continues to tell my daughter when the baby is born he is going to take me to court to have support reduced. I understand and agree that he should have extra money for the new baby. I'm curious on how much support will be reduced since I am living pay check to pay check currently and want to plan for the change.