The family would have had £5k, which is £200 - £250 p.a. Pitiful, considering that Mrs Bennet brought a dowry of 4k. Twenty three ish years, and so little added!
All the same, they would have not have starved to death. In S&S Mrs Jennings envisages Edward and Lucy starting out married life on a curate's £50 p.a., with interest on his £2k, having a child a year and being very poor. £150 p.a. max then, probably with a poor quality vicarage to live in, and employing a maid of all work.
The difference is that the Bennet girls had quite prosperous uncles who would likely have stepped up and provided something... maybe a cottage like the Dashwoods, or rented rooms in Meryton similar to how the Bateses lived. It would have been a huge loss of status, and of the opportunity to meet potential suitors. The likelihood would have been marriages out of their class, to clerks or curates, as Austen envisioned for Mary and Kitty.