To view the statistics information for your channels click on the 'Dashboard' tab on the left hand side of the interface. After clicking on 'Dashboard' you can click on 'detailed view' to see more information per channel.
Alternatively, click on 'Performance' tab in the top middle of the page. The performance tab provides information on your channels. Each channel is automatically assigned with a unique color so you can easily distinguish the differences in the graph. You can see the amount of items you have imported per channel, the total amount of items imported for the past 30 days and also the last time your feed was updated.
You can change the date range in the detailed view of your Google Analytics dashboard. To do this, click on the calendar in the top right corner and then choose a date range in the list and click on "Apply". You can also customize the date range by selecting "Custom range".