I drank about 20 beers on Saturday night and stopped about 10 pm. I have to do an EtG Tuesday night at 7 pm. Approximately 69 hours. Will I be OK?

With THAT much alcohol... and the fact alcoholics have impaired liver function... it could go either way.

I highly suggest checking yourself into a treatment program... AA or some other. That's beyond binge drinking and enough alcohol to cause blackouts or alcohol poisoning for some individuals. Even if you do manage to pass the test... you still are far from being OK. Drinking like that has serious long term negative effects on the body.