Calculus and Optimization
Functions of a single variable, limits and continuity, differentiability and the mean value theorems, Taylor series, maxima and minima, single-variable optimisation (including gradient descent and Newton's method), and the integration you need for probability.
Calculus has carried about 8 marks in both GATE DA papers analysed so far (third-party analyses). The syllabus is deliberately narrow — single-variable functions only — so the questions are usually quick if you know the standard limits, the derivative rules, the Maclaurin series by heart and the first/second derivative tests.
What the syllabus lists: functions of a single variable, limit, continuity and differentiability, Taylor series, maxima and minima, optimisation involving a single variable.