During 1962 War, India had adequate army brigades in reserve to launch a counter attack in coordination with the Air Force. The Chinese Air Force was weak in comparison and positioned far away without midair refueling capabilities. Across the border, Chinese infrastructure was fragile and the supply lines were long and vulnerable. Their appreciation was correct that in any well-planned counter attack by India, the PLA would be hard-pressed to defend itself, particularly as harsh winters were setting in. The Chinese, therefore, intelligently announced unilateral ceasefire and withdrawal from some areas.
In the last fifty years, the government did not build infrastructure in the Northeast or alternatively provide aerial wherewithal to enhance the mobility of the troops. Chinese, therefore will score goals by over running a fair amount of Indian Territory, simply bypassing major Indian defenses.
These four part videos give complete details about 1962 war and how prepared we are for such eventualities in future.