"...any being whatsoever which possesses some eminent quality out of the ordinary, and is awe-inspiring, is called Kami.”
Details on the goddess Benzaiten can be found here. I have been unable to find any estimates for the number of Benzaiten shrines. My own data base, which now includes 64,252 shrines, has just twelve where Benzaiten is in the name of the shrine or where she is indisputably the main enshrined kami. In many other shrines there are subordinate shrines to her and this number must be quite large, I would hazard a guess at least in the high hundreds, and adding in the temples where she is worshipped may well double the shrine figure. The following three are usually considered to be the Top Three Benzaiten Jinja.
Enoshima Jinja Kanagawa-ken, Fujisawa-shi, Enoshima 2-3-8
江島神社 弁才天 神奈川県藤沢市江の島2-3-8
Itsukushima Jinja Hiroshima-ken, Hatsukaichi-shi, Miyajima-chō 1-1
Hōgon-ji, Tsukubusuma Jinja Shiga-ken, Nagahama-shi, Hayazaki-chō 1664
Benzaiten (Osakada) Nagano-ken, Shiojiri
Senzoku Ike Benzaiten Tōkyō, Ōta-ku