I have a friend who is coming to California and he wants to know how long he can stay here on a visitors visa. He would eventually like to live here. So basically how long is a visitors visa good for with someone coming from England to the U.S.

A Visa usually allows a visitor to stay for six months, but bear in mind that it does not guarantee entry. An immigration inspector at the port of entry determines the visa holder's eligibility for admission into the United States.

Duration of stay depends on immigration officer's consideration, maximum term is 6 months but not everyone gets six months.