Will my cat get lonely? (While on vacation)?

I'd agree, he'll be fine, especially as he has visitors to interest him. He'll be glad to see you back but he won't suffer in the meantime. He'll feel more comfortable if he already knows his visitors, so ask 'em over to get to know him, if that isn't already the case.

if your brother and bff are there, i guess he will be fine

If your brother and friend will be with the cat, he will not get lonely. WHY are you leaving a feeder out? They should be giving your cat a meal twice a day (better canned then any dry). If you are feeding dry the entire time you are gone, then your cat could end up with a UTI - are your brother and friend aware of getting the cat to the vet and know the signs of a UTI?

He probably won't be lonely with your brother there and your friend coming in to play with him, but if he is very attached to you he is going to miss you, but since you have someone staying at the house I'm sure he will be fine. He might be a bit mad at you when you come home though as he might think he was abandoned by you since its 5 weeks, but I am sure he will forgive you with lots of attention and a few treats lol.

He sounds like he will be fine,all most cats do is sleep and eat.

Set up two feeding and watering stations in different parts of the home. Also set up an extra litterbox because you don't know how trustworthy these people are.

Leave a note to your vet that it's okay to treat your cat if they take it in.