Is arrhythmia curable?

Maybe. There are many types of arrhythmias, and the answer depends on the type. Atrial fibrillation can be controlled with medications or cured with an ablation procedure. Ventricular tachycardia often requires a pacemaker/icd or an ablation procedure. Ventricular fibrillation is deadly if not addressed immediately. There are multiple others, and the treatment ultimately depends on the arrhythmia type.
Many are. Many types of arrhythmia are due to microscopic electrical pathways or very small groups of heart cells that cause an abnormal heart rate. These types of arrhythmia can usually be cured with a catheter procedure known as ablation. Less commonly a surgical approach is used to cure some arrhytmias.