Articulation Intertwined
If you use any of my warm-ups, you'll notice there is a decent amount of "start and stop" within an exercise. That's on purpose. I'm a firm believer in constantly practicing how we start and end notes. Students need consistent reminders. I would opine that the air overwhelmingly initiates the sound, and the tongue just helps provide a little clarity.
Articulation Connected
For me, articulation comes as the third focus point, after long tones and flexibility routines have been established. We want the embouchure and sustain "set," so when we add the tongue in, its impact is minimal.
Without getting into the specific pedagogy of each instrument, we can say that, generally, the tongue briefly separates the air without stopping it. One way to think of it is that the air pressure is so firm and consistent, it pushes the tongue right out of the way.
I've always liked the analogy of quickly moving your hand underneath a faucet of running water, with the water representing air. The air never stops; the hand just briefly interrupts it.
