In fact, persuasion of any course should be done as per willingness and inclination of an aspirants and as such there is no question of confusion for your further perusal of your studies for any specialised branches. Going through the benefits of each course, you cannot at arrive at which one is better. By clearing CAT, you can land into a job relating to management and by opting for IIM for the persuasion of the Management - course, you will secure your future with a high profile job thus attaining both prestige and huge income from the top fortune companies. So going ahead in that direction would be your own choice.
Securing a high percentile in the GATE score, will widen your future prospects to carry out M. Tech from a distinguished institutions like IIT or from any regional college. If you're interested for a job in the public - undertaking as a management trainee, you will be preferred as a result of your high GATE scoring and some organisation offers additional two increments in the wake of achievement of M.Tech degree.
Hence before you take any admission for the two said courses, a serious consideration from your end is required.