There are several examples of Jane's strong and determined character n the novel. One is that she doesn't become consumed by anger and rebellion despite her appalling experiences in the household in which she grew up and at the boarding school she attended. She realises that survival will mean conformity, humility and exercising upright principles. We see her strength clearly come through again when she refuses to take up Mr Rotchester's offer of moving to France to be his mistress. She resolves to leave the situation altogether, despite the fact that it will leave her destitute.

Jane is a strong woman, and one of the pieces of evidence for this is her reaction to Mr. Rochester.  She does not back down.  She holds her own in conversations, not at all typical for a Victorian woman.  Consider when Rochester asks her to marry him, even though he is married.

“Do you doubt me, Jane?”
“Entirely.”
“You have no faith in me?”
“Not a whit.” (ch 23, p. 184)

Although this is funny, it is also a good example of her strength and strength of character.  She is not willing to be a mistress, but she is also able to speak her mind. She does not let his status, her status, or the fact that he is a man to intimidate her.