Firstly I would like to mention you that GATE is really a tough exam to crack on.Here are the details regarding syllabus
Section1: Engineering Mathematics
Section 2: Digital Logic
Section 3: Computer Organization and Architecture
Section 4: Programming and Data Structures
Section 5: Algorithms
Section 6: Theory of Computation
Section 7: Compiler Design
Section 8: Operating System
Section 9: Databases
Section 10: Computer Networks
Gate exam consists of 3 portion: Technical, Mathematical engineering, Aptitude.
Exam is divided in 3 slots.1st slot is for technicality examinations. 2nd and 3rd slots are common where you will have to choose one portion while another portion are compulsory.
This year exam is conducted by IIT Roorkee. It also published revised syllabus for exam. You can surely take help from this.
Syllabus is available on the site: ” http://gate.iitr.ernet.in/wp-content/uploads/2016/07/Syllabi_GATE2017.pdf ”
Have a look on syllabus.
All the best.