For a good idea of how hard it is to overcome, the Oilers were 19 points behind the Canucks on Dec 20th, the day before the start of the 16 game win streak with 4 games in hand on Vancouver. Fast forward to January 28th, the day after the Oilers had won their 16th game in a row. They still sat 12 points behind the Canucks with those same 4 games in hand. Granted, the Canucks were on a little run of their own at the time so they didn't make up much ground. Vegas, who was 20 points ahead at the start of the win streak (also had four games in hand on), had seen their lead shrink to 5 points (and the Oilers still had five games in hand).
The Oilers would eventually pass Vegas, but they never passed Vancouver and finished the season 5 points behind them. The team went on an insane 46-18-5 run when the coaching change was made but we still never really got close to Vancouver.
It's not just about the Oilers having to win games, it's also about the teams ahead of them losing. What also hurts the Oilers in this case is that they have no tiebreakers and have already lost one matchup to the Knights. To win the division, the Oilers would have to pass 4 teams of which they only have a single game in hand on. I'm not saying it can't happen but we need to start stringing together some wins.
In general, the teams that are far ahead tend to stay ahead. Calgary will likely eventually fall off but I don't think the Canucks, Kings, and especially the Knights are going to tumble.