Yep. I am pretty sure some 7-9 teams have gotten in before.
8-8 is the worst regular season record to make the playoffs...in a non-strike season, anyway, and a number of teams have done that...including the '85 Browns, who faced Miami in the first round of the playoffs.
In '82, when the NFL went on strike after week 9, the NFL did the fluke thing where they increased the number of teams in the playoffs to 8 per conference to make up for money lost. There were two teams with losing records to make the playoffs that year, Detroit and Cleveland, who were both 4-5.