If you are using Xamarin and you need this answer you can use this code:  
//return true if this option is not supported.
public class NotificationsUtils 
{
    private const String CHECK_OP_NO_THROW = "checkOpNoThrow";
    private const String OP_POST_NOTIFICATION = "OP_POST_NOTIFICATION";
    public static bool IsNotificationEnabled(global::Android.Content.Context context) {
        AppOpsManager mAppOps = (AppOpsManager) context.GetSystemService(global::Android.Content.Context.AppOpsService);
        ApplicationInfo appInfo = context.ApplicationInfo;
        String pkg = context.ApplicationContext.PackageName;
        int uid = appInfo.Uid;
        try {
            var appOpsClass = Java.Lang.Class.ForName("android.app.AppOpsManager");
            var checkOpNoThrowMethod = appOpsClass.GetMethod(CHECK_OP_NO_THROW,Java.Lang.Integer.Type,Java.Lang.Integer.Type,new Java.Lang.String().Class);//need to add String.Type
            var opPostNotificationValue = appOpsClass.GetDeclaredField (OP_POST_NOTIFICATION);
            var value = (int)opPostNotificationValue.GetInt(Java.Lang.Integer.Type);
            var mode = (int)checkOpNoThrowMethod.Invoke(mAppOps,value, uid, pkg);
            return (mode == (int)AppOpsManagerMode.Allowed);
        } catch (Exception) 
        {
            System.Diagnostics.Debug.WriteLine  ("Notification services is off or not supported");
        } 
        return true;
    }
}