Student visa is issued only to students, who come to Russia on an exchange program or for education (full-time or part time study, language courses, individual language or research training). This type of visa is available to you only, if you applied to a Russian university, school or an institution and were accepted to study there. In that case, you will need to provide the university with your data and the Department of External Affairs of the university will take care of all the formalities.
Usually, a student visa doesn't have a limited validity, but it is extended repeatedly depending on how long you will study at the university that has provided you with the invitation. This means that with the invitation from a university you may apply for and receive a one-entry student visa that can be prolonged for the whole period of your studies upon your arrival.
If you plan on studying at some other university in Russia than KFU, we recommend you to contact directly that university and solve all issues related to the invitation and visa with them. You should never use services of a company that promises to settle your immigration issues fast.