No that is not confirmed. The creators (said in an interview) began the project with a five year plan which is not uncommon with tv shows. So the show could definitely run beyond 5 years. Now that the show has been commissioned for the 5 years the can start planning for the possibility of 6.. 7.. 8 etc.
posted over a year ago
The writers of the show confirmed it last july At San Diego Comic Con. The fifth season s on the way.