6 million worldwide
This religion is "Bahá'í Faith", not "Bahaism", by its followers. Estimates on the number of followers are around 7 million worldwide.
The religion is not exactly called "Bahaism", though you may find this term sometimes, especially in older literature. The official name is "Bahá'í Faith". - The believers are called "Bahá'ís".
About a billion people.
There are 13 members.
May Maxwell has written: 'An early pilgrimage' -- subject(s): Bahaism
There Are 435 Members In The House Of Represenitives.
Approximately 12 million people.
They have around 80 church members. Most of them are family members.
799000 people
A lot
That would be "Bahá'í Faith", rather than "bahaism". - Similarly to many other religions, there are claims in the Bahá'í Faith about their Holy Scriptures being revealed by God (the Bahá'í Faith is monotheistic), through special messengers. If you accept those claims, that would make the bearers of the message (i.e., the founders of the Bahá'í Faith) holy, as well as the books considered by Bahá'ís to be divinely inspired.
It depends on how many people live there.