I never had issues with GERD / acid reflux, but I imagine if alcohol is the main cause then it will improve or completely go away once sober.
Examples, my anxiety, panic attacks are gone. Redness and puffy face is gone, normal bowel movements, excellent sleep, pin & needle feeling in my toes have gone away, blood pressure lowered, peace of mind and sharp concentration.
If neurogenesis in the brain happens at 48 hours and then two fold neuro-burst at 7 days when sober and continues months sometime years (one reason people feel different in early sobriety the brain does rebuild and enlarges by fluid the brain is rebuilt and slightly different), alcohol induced GERD will go away.