https://www.metv.com/stories/ann-b-davis-revealed-just-how-alike-she-and-alice-really-were

Where did the actor and character divide?

She WAS Alice and did a good job also :)

Ann has said in much later years when her cook book came out that she was nothing like the character of Alice. She could not cook at all and people gave the recipes for the book. It was also reported that Ann was not thrilled to be around kids. Although she loved her castmates, I have heard many of them comment on that too.
On that Sally Jesse Raphael interview from the late 80s she said all actors play parts and she was nothing like the Alice character. I am paraphrasing of course. But I do get her drift that as the series went on, the writers took note of the actors true personality and tried to insert that into the scripts.