How to disable link button if GridView is not present in a page

You needs to apply the following line of code change the ID of your gridView, Once again I would request you to make the link Visible="false" as I mentioned In My very first reply to this thread, then just add a single lile of code beneath your gridView bindig code it would definitely work.

//Your grid view bindig code you may not necessarilly have the same ID of the girdView as
            // "GridView1" so replace it as per requirement.
            GridView1.DataSource = dt;            GridView1.DataBind();
            // The line of code which make the link visible only if data is available in the Grid.            
            Page.Master.FindControl("LinkButtonExport").Visible = GridView1.Rows.Count > 0;