It's not a question of how many people you have, it's how you lead. All other things being equal, of course, a leader can do more with more votes behind them. But all other things are rarely equal!
Even in the minority, a well-led bloc of legislators can accomplish a lot. For example, if the minority had been able to persuade Senator Collins to vote differently on a certain Supreme Court nomination when she was in the majority, things would be very different now. On the other hand, a poorly-led majority, like what Senator Schumer has, might as well not be a majority at all.