There weren't many at all. The height of Russian population in Russian America was about 700 people.

Russian-America was settled mostly by people employed by the Russian-American Company looking for furs, the Russian military sent to secure the holding, and Russian Orthodox Missionaries. The Russian Orthodox Church had asked that able-bodied and available Clergy and Monastics head to Russian Alaska to Enlighten the natives there. Some well known figures, such as Saint Herman of Alaska, packed up and made the 8,000 mile journey to answer the call. By the sale of Alaska, the majority of Russian presence in Alaska was that of the Orthodox Church.

There were a handful of Russian settlements, but the majority of them were forts established by the Russian military. Sitka was the de facto capital of Russian Alaska. At the height of Russian America, there were 90 Orthodox parishes in Russian Alaska with membership somewhere around 20,000, but the vast majority of the attendees were local peoples. (Like I said, the peak Russian population was only about 700.)

The Orthodox monks and missionaries became heroes to the local inhabitants. They raised concerns of the violence Russian soldiers carried out against the Aleut and Kodiak and mistreatment at the hands of the Russian-American Company. Saint Herman was criticized by the Russian Governor Baranov, but in the end the Orthodox monks and missionaries ended up outlasting the Company.

In 1867, the Russian Empire sold Russian-America to the United States for the modern equivalent of about $180-190 per acre. The Russian-American Company was liquidated. The Russian military were sent home after closing their forts and transferring power to American General Jefferson Davis (not the Confederate). General Davis ordered what could have been a Third Amendment violation, removing Russians in Sitka from their homes.

That population of 700, plus any Alaskan Creole, were given the option of becoming citizens of the United States if they chose to stay in Alaska for about three years. The majority of Russians in Alaska, after the sale, returned to Russia and many others emigrated to the Pacific Northwest. Those that remained were primarily Orthodox missionaries, their Aleut and Kodiak disciples, and Creole descendants.

#References

The Orthodox Faith, Volume III, Church History by Father Thomas Hopko.

Welcome to the Orthodox Church by Kh. Frederica Mathews-Green.

Lives of the Saints as published by the Orthodox Church in America.