If you actually look at those studies, the overwhelming majority of predation is caused by feral cats, and even then the things they are killing are vermin - rats, mice, and rabbits. Those are things that humans want to kill in any case. There is no association between cat predation and bird populations. The drop in the wild bird population is caused by habitat loss, and that is being driven by industrial agriculture. In cases where cats have been associated with species decline it's in situations where humans have caused habitat loss by building houses there - so that's rather bolting the door after the horses have run.Quite a few people already doing it in this thread (not?) surprisingly. Also hilarious citing personal anecdotes about their own cats or seeing no decrease in wildlife in their areas...
There are people with specialized educations, doing non-partisan studies that cover multiple years, data source, etc, etc... but people will still say "lol well ACTUALLY..."
Keep your cat indoors if you want, but the idea that cat predation is a key driver of species decline is tendentious at best. Even the main bird charity in the UK, the RSPB, doesn't think there is a strong conservation argument to keep your cat indoors.