Some writers use the excuse that they don't want to be influenced by what other people are doing -- as if they would have no control over what they were doing and might be impelled to copy ideas or plagiarise actual phrases or sentences. That's a rather naive attitude. Ideas sometimes seem to have a currency -- there's nothing worse than finishing a short story or a book, feeling that satisfaction, then picking up a new book for relaxation -- and there's your idea! What a gut-sinking moment. Only, you know they didn't copy it from you, because your version isn't even out there yet. And you didn't copy it from them, because you hadn't read this book before.
Still, if the book's been published, people might think you've copied whether you have or you haven't. So aren't you better off being aware what's out there so that you can make sure yours is different? How else are you going to become aware of the cliches of your genre?
Fine, so you should read widely in the genre you're writing in -- and I maintain you should write in a genre you know and love, not one that you don't respect but think is easier (is there such a thing?) or that is more likely to make you money. If you don't have absolute respect for the genre, it will show through in the writing. Fans will sense the disrespect and respond to it -- even if they can't put a name to it. But is reading widely in your genre enough?
You need to read widely to teach yourself how to write well, and if you are already writing well, to keep raising that bar. Different types of fiction will teach you different things. Want to know about suspense? Go read some crime. What about language use or characterisation? Look at lit fic. Plot? Try a thriller. Experimental fiction might help you take risks you'd never even thought about. Who knows where you might end up? But if you don't read, you won't ever know.