It is always hard to know exactly how many people follow any religion since no one goes around counting; but best estimates are somewhere around 400 Million Buddhists world-wide.
How many people in the world practice Buddhism?
The practice of Buddhism is expressed in many different ways in the US. Some people may practice privately in their homes or they may attend Meditation centers or Buddhist centers.
Between 0.8 to 3.25 percent of people in India practice Buddhism.
Buddhism evolved by that buddha shared his knowledge around Asia and the followers decided to become Buddhism. Today in 2012 there are not many people that believe in Buddha.
Buddhism is practiced all around the world by all peoples. It has not be confirmed at present if there are Inuit, Lapp, Inca or many other groups who are practicing Buddhists, but there are no hindrances to that possibility.
There are no 'holy' people in Buddhism. Many people in Taiwan practise a syncretic religion of which Buddhist practice only forms a small part. However, in recent times Tibetan Buddhism has been gaining popularity.
Around 0.1% of the population, mostly by east Asians who have migrated to South Africa.
The number of people who practice Nichiren's Buddhism depends upon whether you're counting the Soka Gakkai/Soka Gakkai International or Nichiren Shoshu. within the SGI is in 192+ countries/territories around the world I'm unsure of the exact number of members. I have no idea about Shoshu as I am not affilliated with them.
Buddhism has about 365 million followers at the moment.
535 million people
The main religion practiced in Vietnam is Buddhism. Many followers of this religion practice a mixture of Mahayana Buddhism, Taoism, and Confucianism.
There are many times more people in the world practicing Christianity than Buddhism.