What religion is closest to being like fictional Jedi: Taoism, Buddhism, Shintoism, or some other faith?
Jedi was a mix of many... including Christianity (what with the chosen savior born to rescue the people from their life of slavery)
I would say Scientology.
You hit the nail on the head. Lucas is what is definitely an aficionado of eastern religions. I'd say that fictional Jedis subscribe to a faith that is most similar to Taoism and Buddhism, with a very different interpretation of the Tao. Not so much Shintoism, as Shintos primarily believe in spirits, but I've rarely heard Jedi speak of spirits.
Jedi most definitely,
all of the other have been around at least 1000 years.