One of my relatives has done his PhD from IIT Guwahati and he shared his experience of the same. PhD and placements don’t go hand in hand as the goal of most PhD students is to research work and not get employed. IITs and IISc especially have very few job opportunities for Ph.D. students. Very few students around 3-4 from every department complete their Ph.D. every year.
My uncle told me he had 3 offers before submission. In IIT, it usually takes 4–6 months to get thesis review after submission, and an additional month for final defense. A few students get PostDoc and even job offers from foreign universities and companies.
All in all, it takes 5-7 years to get a Ph.D. degree but mostly the placements are satisfactory. My uncle too has become an assistant professor at IIT Guwahati.