How many ports are supposed to be ooen on my tmobile internet modem and if only a few there r like 50 open on mine and i want to know how to close them off

According to the document I read regarding the T-Mobile gateway they do not run a firewall on the appliance. I assume T-Mobile does run firewall content filters on their routing switches within their CGNAT network infrastructure but I have no information about that. 
The gateway has limited functionality for configuration and there is no indication of any filtering possible. Clients on the local network should have firewalls. If additionally you want improved security and control adding a mesh router solution or simply a wireless router with a good firewall and connected clients behind its WAN interface should meet the objectives. There are various conversations regarding adding the additional router so I am not going into all that. Double NAT is a consideration and the fact that dual stack IPv4/v6 and possible multicast issues to resolve so it takes time and focus to do.