Fact: Jane did fall in love with Tom Lefroy when she was twenty. More info here.
Fiction: Tom was a good guy, not a lout (Jane described him as "gentlemanlike" and others describe him as being quiet and shy), and it's unlikely they saw each other after he left Hampshire the first time.
Fact: Henry, one of Jane's six brothers, and her favorite, was handsome and charming and full of energy (and tall). He flirted with their cousin Eliza (who was ten years older) and eventually married her. After she died, he became a clergyman and took over the parish at Steventon where Jane grew up.
Fiction: Henry was not a lout either -- adventurous, yes; drunken partying with women of ill repute, no.
Fact: Jane's cousin Eliza spent a number of years in France, married a Frenchman who was guillotined, and enjoyed her ability to flirt.
Fiction: She was first and foremost English, though she could speak French like a native, and if she liked to flirt, well, that's different than how she's portrayed in the movie. She would have been compelling and lively, but her actions here stretch credibility.
Fact: Anne Lefroy was Tom's aunt and Jane's dear friend.
Fiction: In the movie Anne barely says two words. She was incredibly intelligent and kind and a mentor to Jane. She is the one who stepped in and sent Tom home when she saw they were getting too attached, which was to say the least a bit difficult, but she and Jane had an incredibly close relationship.
Fact: The gentlemen pursuers are not entirely fictional here -- there was an awkward clergyman (Samuel Blackall) who liked Jane and may have been a model for Mr. Collins. And there was a wonderful kind (and rich) if somewhat awkward young man in the neighborhood -- Harris Bigg-Wither -- who proposed one night. Jane accepted then changed her mind overnight and left the house in disgrace. There was also a John Warren, a former pupil of Mr. Austen's, that some thought was in love with Jane, but it seems they were just good friends.
Fiction: So, Mr. Wisley in the movie -- and his aunt Lady Gresham -- are fictional.
Fact: Jane's second oldest brother, George, was mentally disabled in some way and had fits. It's possible he was deaf and dumb.
Fiction: He lived with the Austen family for a while, but was eventually sent away to another village to be cared for by a family who also took care of Mrs. Austen's brother, who had similar difficulties. There is a reference to Jane talking with her fingers, so perhaps she did communicate with him that way.
Fact: Cassandra's fiance, Tom Fowle, did die in the West Indies. All of that was unfortunately true. They had been engaged almost five years, and were only waiting to have enough money to marry. Long engagements were very common when money was an issue.
Fact: Jane and Tom did banter about Tom Jones. A bit risque, perhaps, but Jane would have enjoyed the joke. And she never liked Fielding as much as Richardson, precisely because of the way they handled questions of morality.
Fact: Finances were tight in the Austen household.
Fiction: By the time Jane was grown up, while things were always stretched a bit it seems, the family was not in dire straights, and Jane's brother Edward had been adopted by a wealthy family (a long story) which gave them all some sense of security.
Fiction: George and Cassandra Austen, Jane's parents, seem to have married for love and loved each other deeply. So, the movie's portrayal is a bit harsh. Once, when the boys were small, Cassandra went to help her sister in childbirth, and George wrote to his sister-in-law, “I don’t much like this lonely kind of Life,” and when he talked about the family possibly paying a visit, he said, “I say we, for I certainly shall not let my Wife come alone, & I dare say she will not leave her children behind her.” You can just see the country rector, who did not marry until he was almost thirty-three, in his rather plain small house, missing his dear wife. George had a wonderful disposition, described as “bright and hopeful.” Cassandra, who loved to write small, witty poems, seems to have been full of life.