You can also check the flight status online. You just need to give your airline and flight details. Results is real time data. You can at least get information about terminal but for gate number you will get when airline decides before boarding. You can just google for flight details for your airline. Like fir American Airlines the link is https://www.aa.com/travelInformation/flights/status. Hope this will help you.
Check your ticket, you will find the terminal # and the gate. If not check those big screen at the DFW or ask at any airline desk.. they will guide you. Hope that helps.
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