Yes, you can claim your brother as a Dependent if you meet all of the qualifications. The fact that you were partners in a failed small business does not affect your ability to claim him as a Dependent.
In addition to you providing over 50% of his support, your Brother has to meet these qualifications as a "qualifying relative" in order for you to claim him:
- He isn't claimed as a dependent by someone else.
- He lived with you the entire year.
- He made less than $4,050 in 2017.
- He is a U.S. citizen, resident alien, national, or a Canadian or Mexican resident.
- He isn't filing a joint return with his spouse.
