Everyone hates interviewing, on both sides of the desk. (There may be some rare exceptions to this rule, but trust me, they are rare.) So it's really tempting to cancel all your other interviews and stop applying. But don't.
Sure, sure, because (downer, bummer, pessimist) you might not get this offer and you might still need these other jobs.
But really because these are free interviews with nothing to lose at a time when you have demonstrated that you are really good at spotting jobs you're qualified for, applying to them, getting chosen for an interview, and doing well enough at the interview to cause a director to believe you should get an offer! It's rare that any of us can walk into situations knowing we're good at them. In fact, that's what most of hate about interviews: we worry we're not going to do well at all. But you already know that you did great at least once! And what's more, if you mess up this interview, it probably doesn't matter, because you're probably getting an offer. So you have nothing to lose! Go to your interviews. Enjoy them. Observe how they work. Notice when you are doing it right (you'll have more processing power for this, because you won't be worrying if you're going to get an offer or not.)
What might happen? Well, maybe none of your upcoming interviews are a great fit and they don't make you an offer but this current one does. Great! That's the same as if you cancelled those other interviews, but you had a little less leisure time because you went to them. Ideally you learned from them more than enough to justify the time. Or, possibly everyone makes you an offer and you have a choice to make. That's a great problem to have. Or, possibly the current offer never materializes, but one of these other ones does, and you can pat yourself on the back for having hung in there just in case. I suppose it's also possible that everything falls through, and you have no offers, but at least in that (super unlikely; you've already aced an interview) case, you'll know you did all you could and didn't commit hubris by cancelling the interviews you had scheduled, or stopping applying to likely-looking jobs.