Sorry, please don't notice my first massage. I got a mistake in my mind (is that correct?)
But you really don't add "to" befor "help". Only my example was wrong
You don't have to add "to" because "and to help" doesn't work in that case.
They spend money to help victims of the disaster in Asia.
They spend money and help victims with the appropriation of clean water.
Actually, I just wonder if not adding "to" before help would confuse the readers. If I don't so, would they take the sentence as " It is used to give a helping hand to the poor and it helps them to maintain their lives."
Even after your explanation it sounds odd to me. But it doesn't matter, because it is not wrong when I don't use "to"
Thanks a lot for your explanation
But. . . Dany, the following two sentence are Standard English:
EX: It is used to give a helping hand to the poor and to help them to maintain their lives
EX: It is used to help them to maintain their lives.
I gather you were focused on the prepositional phrase 'to the poor' and the to-infintive phrase to help', right? You're right about the first 'to'. It's a preposition, whereas the second 'to' is not. It's the to-infintive, but that infintive is not conjoined with 'to the poor'. On the contrary, the conjunction "and" joins it with 'to give', so, and as tdol pointed out, with or without 'to' is possible:
It is used to give. . .and to help. . . .
It is used to give. . .and help. . . .
You're right about it not being wrong if you don't use it, but, you see, other speaker do in fact use it. It's Standard English.