"I take it..." is a slightly formal phrase which means "It seems..."
For example, if you came home late in the evening, and there's no dinner, you might say to your family:
I take it you ate already?
If you're at a sports bar, and someone sitting next to you is watching a baseball game on the TV and cheering whenever the New York Yankees score a run, you can start a conversation by saying:
I take it you're a Yankees fan.
This expression comes across as kind of cool and understated.