Some, but it was all but drowned during the immigration surge of the Klondike and subsequent gold rushes. After the Alaska Purchase, the assets of the Russian-American Company were sold to Americans, and most Russians left the territory. In addition, many creoles (the product of marriages between Russian men and Native women) who felt kinship with the Russians also left, most returning to Russia.
Unfortunately, the 1870 U.S. Census did not cover Alaska, so the 1880 census is the first we have to examine. Ivan Petroff, the special agent in charge of gathering information, did an admirable job for the task he faced, and while he was a notorious liar in later years, the census seems to be a fairly accurate document in most respects.
Petroff (or Petrov, it varies), charts the settlements of creoles and remaining Russians at Ninilchik, Kenai, Afognak and through the Aleutians. He discusses religion along the coast (mostly Orthodox) and in the Arctic coast region.
Of the latter, he says:
"No trace or shadow of Christianity and its teachings has found its way to these desolate regions, the dark night of shamanism, or sorcery, still hanging over the human mind."
Of the former:
"The parish priest of the Russian church located at Kadiak village has under his spiritual jurisdiction nearly the whole of this division (Kodiak), with the exception of the western coast of the [Alaska] Peninsula and the upper portion of Cook's Inlet, the latter section being confided to the care of a missionary monk located at Kenai, on the Redoute Saint Nicholas."
He discusses schools, but we know from other sources that support of Orthodox schools was greatly diminished after the Purchase, as the RAC had been required to support these and the church with direct subsidies. When the RAC vanished, so did the subsidy.
During the 1880s, there was an upswing in other Christian missions, particularly in Southeast Alaska. These missions established schools, and I'm sorry to say, were of the "beat the Indian out of you" variety, by and large. In 1885, Sheldon Jackson, head of the Presbyterian Mission in Alaska, was named the U.S. Agent for Education in Alaska.
He proceeded to literally carve the state up among various Christian denominations, each of which had charge of setting up missions and schools in that particular region. Jackson preserved for the Presbyterians the seemingly lucrative Southeast Alaska.
Ironically, this surge in mission work led Natives ─ particularly Southeast Natives ─ to enter the Orthodox church in larger numbers. The American missionaries were harsh, violent and forbade the use of any language but English. The Orthodox priests conducted services and lessons in the vernacular and had the benefit of two centuries' worth of accommodation.
By the time of the Klondike Gold Rush, however, things were rapidly changing. The 1880 census found only 430 white settlers out of 33,426 people. By the 1890 census, the Juneau Gold Rush was 10 years old, and the proportion of whites was up to 12-13 percent. Juneau alone had three times more white people than were present in all of Alaska just 10 years before.
In 1900, Alaska was just shy of half white. By 1910, it was 55 percent white. WWI drove miners out of the territory in droves ─ Alaska wouldn't return to 1910 population figures until 1940 ─ but by then, the Americanization swing was well under way. The Bolshevik Revolution and subsequent Russian Civil War cut down regular contact between Russia and Alaska, and in 1948, it ended entirely.
A trace of Russian history remains today ─ Alaska's population, according to the 2010 census, is 12.5 percent Orthodox. That's a higher proportion than any other state in the United States.