Even as the Russian Government is yet to decide where it stands regards Cryptocurrencies, Kaliningrad, hosting 4 matches, has decided to accept Bitcoins as payments for hotel rooms. Free-Kassa will facilitate this payments during the world cup. It is expected that other hosting cities will follow suit.
Source: https://www.ccn.com/russia-allows-cryptocurrency-payments-for-hotels-during-fifa-world-cup-2018/