This is an excellent question.

There is no doubt in my mind that the character from Tartuffe most like Sor Juana Ines de la Cruz is Dorine.

eNotes.com provides a character description of Dorine:

...Dorine has a very strong personality and is never afraid to speak out against Orgon or anyone else with whom she disagrees...

Dorine helps to mend the hurt feelings between Mariane and Valère, after Valère learns of the engagement to Tartuffe and assures the young lovers that she will devise a plan to allow them to marry one another.

Dorine is a servant, but she is not one to hold her tongue when she feels an injustice has occurred. She even faces the potential wrath of Orgon (the head of the household) when he arranges the marriage of his daughter to Tartuffe (the charlatan passing himself off as a holy man), telling Orgon he is wrong. When Mariane (Orgon's daughter) and her "intended," Valère seemed doomed to be forever separated, Dorine intercedes with a promise that she will find a way for the two to marry if they need her help.

Sor Juana was a remarkable woman. Reading at the age of three, she had an boundless desire for learning. She read every book in her grandfather's library, under protest from her mother. She begged to be allowed to dress as a boy so that she might attend university, as this was a privilege extended only to young men in New Spain (Mexico), but was refused.

It was not only those around Sor Juana that were particularly demanding of her. Sor Juana was, in many ways, her harshest judge. When she did not learn something within a timeframe she had set for herself, she cut great lengths of her hair off, and continued to do so until she had achieved her goal. Knowing she did not want to marry, but wanting to continue to learn, she joined a convent so that she could continue with her studies.

She was, similar to Dorine—outspoken, with a strong spirit.

Sor Juana also displayed an independence of spirit unusual for a woman—to say nothing of a nun—living in such a male-dominated society as l7th century colonial Mexico. After criticizing a sermon by a well-known pulpit orator...she received a stern rebuke from Manuel Fernández de Santa Cruz, Bishop of Puebla.*

Sor Juana responded with a remarkable letter in which she gave a complete resumé of her life, character, literary preferences, etc. More significantly, the letter also contained statements in favor of "the culture of Mexican women" and "the right to dissent."*

Sor Juana's response is considered by some to be the first feminist manifesto. She was amazing, defending herself in a composed, logical way. Her intellect was obvious in her many accomplishments. Like Dorine, she was prepared to take on the powers that be, even if it meant the Church—her chief desire was to learn, but she could not be silent when she felt that a woman's best interest was not being recognized by the society in which she lived.

Dorine, in Tartuffe, and Sor Juana were both strong women, unafraid to stand up for others or take on the establishment if necessary.

*Additional source:

http://www.mexconnect.com/articles/271-the-remarkable-life-of-juana-inés-de-la-cruz-1651–1695