How many books you will read, It’s depends on you. Because you will read.
Actually it depends on your time and interest. How much time will you get for reading and how much you are interesting on that book?

Remember, one man can not gain on all knowledge. You should try to acquire knowledge on a specific subject and read on that specific subjects book which you have interest.

if you want to acquire knowledge on all subject then he will not get fit for any subject. You will not get full knowledge on any subject. Because you will not get too much time for reading and learning.

Hope you have understand now.