The Bahir is mentioned by name in his Conclusiones (8>15, there called "libro bair"), one of only two Kabbalist works so cited, the other being the Zohar (zoar).The Bahir is a very old book from the kabbala development. If Pico had opportunity to read it, might be doubted.
Online, Google Books has an English translation of the Latin translation that Pico used. In the prefatory material, also in English, there are two sections where the influence of the Bahir on Pico is addressed specifically.
The first, by Giulio Busi, is pp. 43-51, starting at https://www.google.com/books/edition/%D ... v=1&bsq=43
The second, by Saverio Campanini, is pp. 86-98, starting at https://www.google.com/books/edition/%D ... v=1&bsq=86
Pp. 43-51 of this book is also at
https://www.academia.edu/33027817/The_B ... iulio_Busi