Lewis Dot of the Silicon Hexafluoride Ion
Si does not follow the octet rule. It actually bonds. It will hold more than 8 electrons.
Silicon having valence electrons in the 3rd energy level, will also have access to the 4d sublevel, thus allowing for more than 8 electrons. SiF62- is d2sp3 hybridized and contains no lone pair and 6 bonding pairs of valence electrons around the Silicon. The VSEPR predicts the Octahedral shape.
Elements in the first 2 periods of the Periodic Table do not have access to the d sublevel and must adhere to the octet (or duet H and He) rule.