Most of your posts suggest that you feel under a very strong obligation to him for helping you out by listening to your problems and sending you some encouraging texts. That is a VERY easy thing to do that doesn't cost anyone a penny.
Look how many people here have responded to you with encouraging texts. We're not expecting anything back for that and neither would a true friend in RL.
YOU DON'T OWE HIM ANYTHING!! If you want to "repay" him, at most it would be to respond sympathetically to a text or two. But in this case I don't advise continuing this texting. You've told him no, and yet he keeps on and on. Pulling at the heart strings. You actually don't know him well enough to know if any of these sob stories are actually true. The relative, the overtime etc.
You sound so guilty as if his troubles are your fault and you must do all you can to help - even though you can't - even though you've told him no. How have you ended up feeling that way? Could you even consider for a minute if he has made you feel that way? Constantly lading his texts with "Poor Me,Feel Sorry for Me" statements for example.
I think OP that you need to go through some of his previous texts and see what statements can actually be verified, what can be taken with a grain of salt, looking closely at the statements that make you feel guilty and maybe quote some on here to see if they stand up to scruitiny.
I know it is disappointing to feel that someone you trusted who was friendly is not all they seem, but the biggest evidence you have is that he is not taking NO for an answer.
At the end of the day, the solution is so simple. You can't afford to lend him the money and that is that. How he deals with that is his problem. Not yours.