He could not simply read,
hi there:whats meaing of this sentence"
he referes to whom?

So it was concentration on the drawing, but his ability was such
that even though he may not have been fully concentrating on it,
because there were distractions, he would come through with
remarkable works, like one he was doing a take off on Matisse. But the
fact that you have illustrations here. This is Matisse! I mean he caught
the spirit, or what you called “Matisseness.” He could not simply read,
was not simply imitating. It’s more than that.

Question

He could not simply read,
hi there:whats meaing of this sentence"
he referes to whom?

So it was concentration on the drawing, but his ability was such
that even though he may not have been fully concentrating on it,
because there were distractions, he would come through with
remarkable works, like one he was doing a take off on Matisse. But the
fact that you have illustrations here. This is Matisse! I mean he caught
the spirit, or what you called “Matisseness.” He could not simply read,
was not simply imitating. It’s more than that.

Answer

"He could not simply read" probably means "He was not simply reading." or "it was obvious that he wasn't just reading".

Reading text or anything else is a cognitive process involving stages, like parsing the sentence first and then applying logic and your existing knowledge to understand it fully.  What the writer is saying is that the way "he" (the person who did the Matisse style drawing) did his work didn't seem to involve the usual reading process.  He did not pick apart what he saw to make sense of it and then applied his own ideas.  The writer felt that he somehow directly connected with the essence of Matisse's creativity, transcending the usual and mundane "reading" way that people employ when dealing with other artists' works.