If you assume, for sake of argument, each senator represents half of his or her state’s population, then senators voting for the bill represented about 194 million people, while the senators voting against the bill represented about 118 million people. That’s getting close to a two-thirds majority in favor of the measure.
The key to all this is that the undemocratic affect of the filibuster is layered on top of other undemocratic features of the Senate, like the small-state bias and the lengthy election cycle.
George Washington probably never told Thomas Jefferson that the Senate is "the cooling saucer of democracy." But even if he did, he was talking about the Senate at a time when the population difference between the smallest state and the largest state was a fifth of what it is now, when senators were appointed by state legislatures, and when the filibuster didn't yet exist.
For better or for worse, this is not your founding fathers' Senate. The country has changed too much and we've changed the Senate too much to blame today's dysfunctions on them.