Will create an Excel Gantt chart based on a selection that is 4 columns wide (Task Name, Start Date, Days ToGo, Days Completed), and at least 2 rows high (must include a headers row). All series in the chart will be dynamic named ranges, so you can add rows and the chart will pick them up automatically. However, there can be no blank rows in the Task Name data column!
NOTE: VBA Charting between Excel versions is extremely glitchy. Your output may not look exactly as depicted, but it should get you nearly there. This example was created in version 2013.