The infinitive clause, often with subject implied rather than stated, is a common literary figure for placing a hypothetical action before the reader (or, in narrative or drama, before another character or oneself) as a question, or for contemplation.
To be or not to be: that is the question.
The character or reader is depicted as turning the possible action over in his mind: “Suppose I were to do such-and-such?”.
The figure may be multiplied for rhetorical effect; two classic instances in English literature are Hamlet's and Claudio's soliloquies:
To die: to sleep;
No more; and, by a sleep to say we end
The heart-ache and the thousand natural shocks
That flesh is heir to, ’tis a consummation
Devoutly to be wish’d. To die, to sleep;
To sleep: perchance to dream: ay, there’s the rub ...
Ay, but to die, and go we know not where;
To lie in cold obstruction and to rot;
This sensible warm motion to become
A kneaded clod; and the delighted spirit
To bathe in fiery floods, or to reside
In thrilling region of thick-ribbed ice;
To be imprison’d in the viewless winds,
And blown with restless violence round about
The pendant world; or to be worse than worst
Of those that lawless and incertain thoughts
Imagine howling: ’tis too horrible!
So in Brontë's passage Jane is examining, one after another (seriatim is a nice word for impressing your professors), various aspects of what it would really mean for her to embrace poverty, and concluding that the price of liberty is too high.