What factors can influence the survival rate with esophageal cancer?  

Stage & response. Survival rate affected by stage of esophageal cancer and response to treatment (and tolerance of patient to treatment) ...
Quite a few. Survival depends on the cancer stage (early vs. Local spread vs. Distant spread). It also improves if the cancer can be surgically resected or not. Patient factors such as general health, ongoing drinking or smoking, weight loss are also important. Post-treatment factors such as diet, exercise, lifestyle changes are also important.