cat fued?

l adopted a kitten around four months ago. I already have an older cat who I adopted around 7 or 6 years ago.

I thought over time my older cat would become adjusted to a new kitten, but still months later he always hisses at him, tries to hit him, doesn’t let him eat around him or be next to him.

Is there any way I could help him get adjusted to him? He’s just recently started to let the kitten sleep on my bed with him but only as long as he’s not touching him.