Will eating spicy food cause GERD or make GERD worse?

Mechanical. Gerd is a mechanical defect in the valve and sphincter that act as a one way valve in te lower esophagus. Certain food can cause relaxation of the sphincter and aggravate th reflux. If you already have reflux irritation, nthe spicy food can aggravate it like salt water can make a wound burn.
Second. Spicy food doesn't cause gerd but it can exacerbate gerd symptoms. The spices can make your stomach over-produce acid and/or cause irritation in the lining which will cause acid to reflux into the esophagus and eat away the lining.
Yes. Spicy foods can make the symptoms of gerd (gastroesophageal reflux disease) worse, but they can't cause gerd. Patients with esophagitis (a common manifestation in gerd) can feel worse after eating spicy foods or citrus fruits or juices.