The EUR/RUB* rate is also base on the data of Moscow stock exchange. The Central Bank of Russian Federation each working day updates its official rates of EUR, USD and other foreign currencies based on the stock exchange data on 8:30 GMT. These rates become official rates of the next day.
The most up to date EUR/RUB rate is the current stock exchange rate which changes continuously and can be tracked online. At the moment (01.06.2020 19:00 GMT) it is 77.07 RUB for one EUR.
The long-term forecasts of EUR/RUB rates are nearly impossible. However it is possible to predict the rates for the next day. Current EUR/RUB rate is 77.07 RUB. So, it is possible to say that the next official rate is going to be something like it.
* Sometimes RUR code is used as Russian currency code. But RUR is the old code replaced by RUB now.