This popped up on Reddit a couple days ago, and people quickly pointed out that it is (to put it lightly) utter bullshit. The sole source in the article, Andrey Illarionov, is a former Putin adviser who split from the government back in 2005 and has since been apparently putting out a stream of very alarmist and absurd statements about Putin since.
Furthermore, Finland is pretty much nothing like Ukraine: They've got a competent army with a decent stock of modern military equipment in good functioning order, their government is not in the midst of a collapse and/or revolution, they've got allies to call on, and perhaps most importantly there is (to my knowledge) no significant ethnically or linguistically Russian populace to turn into a cause for invasion.
So, some of Baltic states? Yeah, I could see Putin going after those - but not Finland. I'd file this under the same category as the Russian minister saying they're going to reclaim Alaska.