M.Tech

No. GATE is not mandatory, but if you are thinking to do masters in India, then GATE is the best. Even if you spend a year in preparation, no problem, go for GATE.
Without GATE-
1.Career aspect: First thing you can't get into well reputed institutes like IITs, NITs, and some Govt colleges. When you done with you are M.Tech, the college from where you have done your masters is very important. It matters a lot in initial stages of your career. Most of the private colleges in India for name sake they are providing M.Tech degrees, but they don't have required lab facilities and well qualified faculty too, so what is the use obtaining degree from such universities?
2. Financial aspect:You have take care all financial needs by yourself. If you have cleared GATE, you will be getting stipend of 12400 pm,that too in Govt institutes you will have very less fees. Do you know? IIT Kharagpur tuition fee is 5k per semester, including everything ie food+Hostel+internet+medical etc. it comes out 33k per semester. You wont get such low fees in anywhere in India.
Actually any GATE qualified , if he takes admission through GATE in any AICTE approved colleges should stipend of 12400 pm, but it never happened in reality. You know its all government, no need to explain our system.
My advice, if want to do M.Tech, do it in well reputed colleges through GATE. If you are just thinking to get a M.Tech degree, then do it some private colleges.

Study Plan for the M.Tech Entrance Exams:
If the candidate takes some cautions while studying for M.Tech entrance exams, it can be can be as easy as preparing for your college examinations. The students have to focus on the core subjects. Presence of mind is an important factor that is needed for the preparation of such competitive examinations. Always try to follow the standard books that are available in the markets to prepare for the examinations. Prepare key notes while you study as it helps the candidate to memorize the portions very easily. When you are studying a topic ask yourself some questions such as What and How. Keep in mind that the questions are mostly of objective type. Therefore the candidates can expect tricky questions. Regards.

M.Tech Computer Science & Engineering with Choice based specialisation in Artificial Intelligence, Image Processing, Data Analytics and Security is a specialised programme aimed at providing the student with in-depth knowledge of four key domains in Computer Science and Engineering. Artificial Intelligence, Image Processing, Data Analytics and Security and Forensic technologies have acquired widespread acceptance and adoption among enterprise business applications and research community. Several startups in recent times have endorsed the presence of these domains.
Career Prospects:
Artificial Intelligence
Image Processing
Artificial Intelligence
Software Developer
Adaptive Technology Development
Expert System Developer Research
Automation Application Development
Heuristic Programmer Game Development\
Design Industry
Web Designing
Medical Image Analysts
Printing Industry
Radar Sensing and Imaging
Weather Forcasting
Photoshop Retoucher Space Industry
Data Analytics Security and Forensic Operation
Data Scientists
Analytic Consultants
Stock Analysts
Financial Analysts
Business Analysts
Research and Development Software Testing
Cyber Forensic Network
Forensic Security
Architect Security.