I would say 'not intentionally'. I would actually swear I've seen a Tolkien drawing of either Wellinghall or Treebeard's viewpoint somewhere, but I can't track it down. Other than that possibility, I don't know of him ever drawing anything from Fangorn.
... but.
As
WCH has already mentioned:
There is
this painting, which was labelled up as 'Fangorn Forest', but originally painted as Beleg finding Turin in the Nightshade. It's pretty obvious when you pay attention, because the moving figure has a huge long sword at his waist. But
arguably, since Tolkien himself redefined the picture as Fangorn, it could be read as telling us what Merry and Pippin looked like - and theoretically, one of those trees might be Treebeard.
But probably not.
But you didn't just ask about Ents; you asked about Huorns as well, and there's a much more solid answer there. If Huorns are trees which are 'awake', and rather malevolent besides, then there's a strong case to be made that Old Man Willow is one. And Tolkien
did draw
a rather lovely picture of the Willow-man. So (if you accept that OMW is a Huorn) the answer is 'yes'.
... but not intentionally, because Old Man Willow was invented well
before the Huorns, at a time when Tolkien was still using 'Ent' to mean 'giant'.
I have to admit this made me giggle. ^_^
hS