If someone signs up for Netflix to see House of Cards (and other original programming), they will stick with Netflix as long as they can see something they like.
As for the numbers, a new customer who stays a year makes them $88 in income (the first month is free). If 100,000 viewers sign up to see it and remain for a year, that’s $8.8 million. Assuming a $14 million cost, the loss is just over $5 million. But that doesn’t count the number of people who sign up for more than a month – three months, for instance. This can easily make up most of their costs. And House of Cards now becomes part of their stable of shows: If they come out with, say, a renewed Firefly, people will say “Wow, we can see both Firefly and House of Cards!. It’s time to sign up.”
Netflix also know who is watching what. They can easily find ways to aggregate that data so they know what shows are drawing in new subscribers and what old subscribers have watched. They can see that you saw the original HoC in a binge when it first came out, then watched it in a binge when the second series came out. That would show that doing a third series would most likely keep you subscribing.