Can toddler get thrush from a pacifier that hasn't been washed. If I boil pacifier will bacteria come off so he can use again?

Yes, but.... Boiling is an excellent way to sterilize and boiling a pacifier will completely clear it of bacteria. However, thrush is not a bacteria but a fungus. Fortunately, boiling is also effective in killing fungus as well. If the symptoms of thrush continue, see your pediatrician or family doctor for definitive treatment.
Yes. Yes you can get thrush for a pacifier and you can reintroduce it if the thrush is gone in their mouth and you havent washed pacifiers, bottles, etc. Hot, soapy water with a good scrubbing should work too.