What are your chances of surviving ewing sarcoma if it spread to lungs?

Not too long. For metastatic tumors, the five-year survival rate is 20% to 30%. Know if it is spread to the lung alone is better than that.
Ewing sarcoma is... A rare solid tumor of children and young adults, exceptionally rare in adults. It is one of the small round blue cell tumors. The cell of origin is unknown, but gene expression profiles suggest some measure of neuroectodermal differentiation. It's most often characterized by the t(11;22) translocation expressing the fusion protein ews-fli. Localized dz survival 70-80%. Metastatic dz survival ~20%.