What is the oxidation number of Si in (CH3)2SiCl2

Answer 1

well, Dimethyldichlorosilane , you have the formula wrong, consider
Si(CH3)2Cl2

as you can see from this Si has four things attached to it, two methyl groups, and two Cl- ions. Si must be +4
CH3
CH3-Si=Cl
Cl

Answer 2

disregard that diagram, it came out way wrong.