Yes drinking cabbage juice daily can heal an ulcer and you should start seeing the effects of cabbage juice within 7 days which means within 7 days of drinking the cabbage juice daily you should start healing from the ulcer.
And within 30 days to 43 days of also drinking the cabbage juice daily the ulcer should be fully healed.
Cabbage Juice is also a good antioxidant which can detox your body and provides you with needed vitamins to keep your body healthy as well.
So you'll be healing your ulcers and keeping your body healthy as well when drinking cabbage juice.