The Sage Archetype says that "a sage gains 2 skill ranks at each level." So every level it gets 2 skill ranks. Not 2 + INT, and not 2 + 2 + INT. It gets just 2 every level.
Now, it will also get 1 skill equal to its INT mod beyond 0. It doesnt get this extra skill rank every level, it gets this extra skill rank only one time, because it only has one HIT DIE.
A Level 7 Sage Familiar always has an INT equal to 12 (5+7). From this alone, it gets 3 (2+INT Mod of 1) skill ranks. It also gets 2 skill ranks for each Level it is, 14 (2x7). This means it has 17 Skill Ranks.