Can lee sin be grabbed during his Q jump kick?

Solution 1:

Yes he is targetable during the whole flight this means you could even stun him with an udyr autoattack if you are fast enough. A Blitzcrank/Thresh hook is obviously pretty hard to land on a flying Lee Sin but With a thresh E you can prevent him from dealing any damage which is actually pretty easy to time with smartcast on. Here you can see that it is possible with thresh E.

You can interrupt most dashes with hard CC. The only exception to this are dashes which renders the Caster immune to CC (Vi R, Malphite R) or that make him untargetable (Maokai W, Master Yi Q)

Solution 2:

My guess is yes (though I haven't seen this happen before), since Lee Sin's Q and W are both dashes, not blinks. I've seen other dashes get interrupted (one example that sticks in my mind is when Daydreamin's Blitzcrank grabbed someone out of a Thresh lantern during an LCS game).