The Packers are widely regarded as one of the best teams in the league, and they have arguably the best quarterback in the NFL (let's not turn this into a Brady-Rodgers debate now...). They also have one of the best home field advantages in the NFL. So, yeah, no surprise that they're the favorites.
Some NFL odds outlets have the Packers as a 6.5-point favorite while another one has them as a 7.5-point favorite. I am not likely to pick the Chiefs to win barring any crazy injuries in Green Bay but I do think the Chiefs have the type of team that can keep this game close. I wouldn't bet on this game because the Packers have the ability to blow this game open but my score prediction will reflect a competitive game in the fourth quarter.
Most NFL lines are close but there are a couple of bigger lines than the Chiefs-Packers game. The Patriots are a 14-point favorite over the Jaguars while the Seahawks are a whopping 16-point favorite over the Bears.