We studied oscillatory behavior of critical amplitudes for the Gaussian model on a hierarchical structure presented by a modified Sierpinski gasket lattice. This model is known to display non-standard critical behavior on the lattice under study. The leading singular behavior of the correlation length ξ near the critical coupling K = K c is modulated by a function which is periodic in ln | ln(K c − K)|. We have also shown that the common finite-size scaling hypothesis, according to which for a finite system at criticality ξ should be of the order of the size of system, is not applicable in this case. As a consequence of this, the exact form of the leading singular behavior of ξ differs from the one described earlier (which was based on the finite-size scaling assumption).64.60. Ak, 05.50.+q, 05.40.Fb