Charles Dickens had "great expectations" for himself as a novelist, and he drew from experiences in his own life to write his books. One such experience was when he was forced to work in a bootblack factory because his father was imprisoned for debt. He felt hungry and abandoned and dreamed of a better life for himself, much like Pip did working in Joe's forge. This experience stayed with Dickens for the rest of his life and Pip, as well as other characters in Dickens' books, were based on his experiences.
Dickens' first love can also be related to Pip's love for Estella. Dickens felt he was rejected by her because of their class differences. Pip feels this same desire to better himself so he's worthy of Estella.
All of Dickens's books reflect his experiences as a child. This is why you see an emphasis on orphans and children who have been abandoned. Self-pity also characterizes the people in his books. This stems from the self-pity Dickens felt when his mother made him continue to work in the factory even after some of his father's debts were paid.