Since marijuana is still not legal as per the federal law, people are expected to use cash instead of keeping the profit in to banks. So most likely it will increase bitcoin or similar coin transactions. but I doubt there will be an impact in bitcoin market due to that.
Because there are so many alternatives like paypal and perfectmoney.
Yes bitcoin users will increase tremendously when marijuana users will start to use bitcoin as an exchange to purchasing marijuana. IF it happens that they will purchase or buy imported marijuana goods and they will pay a huge amount of bitcoins for a big volume of marijuana then somehow there will be an increase on the price of bitcoin due to higher demands.