public FeatureLayerCreationParams( 
   CIMDataConnection dataConnection
)

{
    //Note: Call within QueuedTask.Run()
    if (MapView.Active.Map == null) return;

    //Get an existing Layer. This layer has a symbol you want to use in a new layer.
    var lyr = MapView.Active.Map.GetLayersAsFlattenedList().OfType<FeatureLayer>()
          .Where(l => l.ShapeType == esriGeometryType.esriGeometryPoint).FirstOrDefault();
    //This is the renderer to use in the new Layer
    var renderer = lyr.GetRenderer() as CIMSimpleRenderer;
    //Set the DataConnection for the new layer
    Geodatabase geodatabase = new Geodatabase(
      new FileGeodatabaseConnectionPath(new Uri(@"E:\Data\Admin\AdminData.gdb")));
    FeatureClass featureClass = geodatabase.OpenDataset<FeatureClass>("Cities");
    var dataConnection = featureClass.GetDataConnection();
    //Create the definition for the new feature layer
    var featureLayerParams = new FeatureLayerCreationParams(dataConnection)
    {
        RendererDefinition = new SimpleRendererDefinition(renderer.Symbol),
        IsVisible = true,
    };
    //create the new layer
    LayerFactory.Instance.CreateLayer<FeatureLayer>(
      featureLayerParams, MapView.Active.Map);
}

{
  // Note: call within QueuedTask.Run()
  {
    var url = "https://geoeventsample1.esri.com:6443/arcgis/rest/services/AirportTraffics/StreamServer";
    var createParam = new FeatureLayerCreationParams(new Uri(url))
    {
      IsVisible = false //turned off by default
    };
    streamLayer = LayerFactory.Instance.CreateLayer<StreamLayer>(createParam, map);

    //or use "original" create layer (will be visible by default)
    Uri uri = new Uri(url);
    streamLayer = LayerFactory.Instance.CreateLayer(uri, map) as StreamLayer;
    streamLayer.SetVisibility(false);//turn off
  }
}