I was in an accident in a big truck while on the job, two years later the occupant of the other vehicle is seeing. Can he sue me personally or is my

Yes, the occupant of the other vehicle can sue you personally.  He can also sue the company you worked for on the date of the accident or he can sue both you and the company.  Since you were on the job at the time of the accident and you were operating a company vehicle (I presume with permission of your employer), the insurance carrier for the company will hire a lawyer to defend you and any money obtained by the occupant of the other vehicle will likely be paid by the insurance carrier for the company.  If you have not already done so, you need to turn over a copy of the lawsuit to the company and the insurance carrier for the company.  You will also need to cooperate with the lawyer hired by the insurance carrier to represent you.  Good luck with this matter.