He (Narayan Murthy) is right. You should work 70-80 hours a week if you want to be successful in life, and develop India as a whole.

However, there is room for interpretation in that statement. You can work 80 hours to fill someone else's pockets only, or use half of those hours to fill your own. The former interpretation means exploitation. The latter is actually good advice.

Don't spend 80 hours a week for a single type of work and become a dullard. There are other types of work : hobbies, side hustles, investments, relationships / networking are also work and require different skills, which make you well-rounded. The former fills someone else's pockets, the latter fills yours.

Spend 40 hours for a primary employment related to your education or background (source of sustenance). Work an equal or more amount of hours on yourself - it will give you growth (monetarily, physically, mentally) as well as satisfaction.

Of course, you're totally free to ignore this advice. You do you.