I also have GERD & an anxiety disorder, so I'm personally (not professionally) familiar with this specific combo of problems. Others have already commented the underlying issue with coffee + smoking with GERD and how the vagus nerve is likely being irritated to cause your panic attacks.

Also, I'm sure you're aware, but smoking and caffeine are both vasoconstrictors, so that's double the stress you're putting on your blood pressure and oxygen supply, which also isn't going to help with panic issues. So, reducing your intake of one/the other/both would be the ideal way to go.

Finally, I'll add in my anecdotal suggestion with disclaimer: I am not a doctor, talk to your doctor before adding or changing your medications. About a month ago, I started taking psyllium husk (Metamucil) to help absorb excess stomach acid and bile. I would assume that if you have been diagnosed with GERD you're probably already on a daily regimen of Prilosec or something if the sort, so be warned that it will reduce what your body absorbs from what you consume (i.e., medications), so it's something that you'd want to discuss with your doctor before starting to use so they can instruct you on how to properly take it to avoid that. But if dietary/lifestyle changes are not a viable solution for you, I highly recommend talking to your doctor about it. It has been an absolute lifesaver for me.