What is the life expectancy of my father in law if he just got diagnosed with stage 2 lung cancer?

Good. Standard of care therapy for stage 2 lung cancer is surgery or lobectomy followed by chemotherapy. Surgery can also be performed minimally invasively or thorascopically.
Stage II. Implies a hilar node (where the bronchus exits th pleura and enters the mediastinum. The new system also includes any tumor size >5 cm despite negative nodes. Five year survivla is < 50%, but abslute benefit with adjuvant chemotherapy may improve that. It is not, however, a rosy prognosis for the group that have these characteristics.