Since GATE is a CBT(online computer based test) you can select the city of your preference while filling the application form.You will need to select 3 centers (2 from one zone and 1 from another zone)of your choice and they will allocate you one center from your preference that you mentioned in the form.for more information read the article,

https://engineering.careers360.com/articles/gate-exam-centres

Hello!!!

Check out this link given below-

https://www.google.co.in/url?sa=t&source=web&rct=j&url=https://engineering.careers360.com/articles/gate-exam-centres%3Famp&ved=2ahUKEwiTusDhs8PbAhUkSY8KHadfDWAQFjAMegQICBAB&usg=AOvVaw2wVRs2K2j1mPJyklVFZqh1&ampcf=1

Good luck !!