Mr. Trump will not be impeached for anything that happens while he is President Elect. The Congress can impeach a President for actions that amount to high crimes and misdemeanors. However, only actions that occur while he is President are actionable. Regardless, President Trump is very unlikely to ever be impeached by a Republican Congress.
Before the election, the democrats thought that it was silly to think that Russia would have anything to do with the election. They said that there was no sign of fraud anywhere. Then, there was an upset. Trump won when everyone thought that he couldn't. All of a sudden, Russia is involved and Trump needs to be impeached.
It doesn't matter what Trump does unless it's so flagrant that the Republican Congress can't ignore it, and his involvement with Russia doesn't meet that standard at this point. If we find out that he was directly involved and broke a law, or if he colludes with Russia in the future they might change their minds.
There are a lot of impeachable offenses that Trump has committed or will commit, but I don't think lying about Russian election interference is going to be the one that gets him out of office. I have no doubt that the man will screw up big time. It's just a matter of how long his Republican puppets will sit back and allow him to act that way.