If a man wants to get a divorce but the wife wont let the man see his children if he leaves her can visitation rights be pressed?

Please go to a family lawyer in your area immediately and get some counsel on how to proceed. There are not enough facts in your posed question to adequately answer your problem.  Generally,  a father is entitled to see his children.  If the Court finds that the gun and drug issues require action, the Judge could order the father to undergo drug testing and might order restricted or supervised visitation with the children.  There are many options that are available and with proper legal assistance, the father should be able to see his children.