Try this to see if it works for you
  p = Plot[Evaluate@Table[PDF[GammaDistribution[alpha, beta], x], {alpha, {0.31867}}, {beta, {268470}}], {x, 0, 50000}, Filling -> Axis]
now in new cell type
  data = Cases[Normal[p], x_Line :> First[x], Infinity];
  data = Flatten[data, 1];
  TableForm[data[[1 ;; 10]]]  (*show first x,y points, etc...*)