Jane asked her sister Cassandra to burn the vast majority of her letters when she died, so that’s what Cassandra did
April Bernard argues that this was a good thing - by the time of her death, Jane must have known she was a success. She was popular among the taste-makers of her day (namely, the aristocracy) and she received some very positive reviews, including one from Sir Walter Scott
Jane must have had some idea that her novels would endure through the ages, and she wanted her novels to stand alone, without the distraction of her private life
Which writers influenced Jane Austen?
She read and studied and modeled her balanced sentences on the writings of Samuel Johnson.
He was one of the best moralists of the age, and a great wit. Sounds familiar?
Jane learned everything from Shakespeare. This is not surprising, as many notable literary critics (including Harold Bloom) compare her works to Shakespeare.
From https://omnia.sas.upenn.edu/story/jane-austens-enduring-popularity:
“In literary circles, however, Austen was known. Her final publisher was John Murray, who also handled Sir Walter Scott, the most popular poet and novelist of his time. The librarian for the Prince Regent, the future George the IV, approached her about dedicating Emma to His Royal Highness.”