× I’ve to do lots of things today.
√ I have to do lots of things today.
× I haven’t to earn a lot of money to be happy.
√ I don’t have to earn a lot of money to be happy.
× Have you to get up early tomorrow?
√ Do you have to get up early tomorrow?
Have is an auxiliary verb in have got, or in the present perfect tense: ‘I haven’t got any brothers.’ ‘Have you been to Italy?’
Have to is not an auxiliary verb, so you cannot use it in a short form (I’ve) and you need the verb do in negative sentences, questions and short answers.