  In this paper, we establish the existence of time quasi-periodic solutions to
generalized surface quasi-geostrophic equation $({\rm gSQG})_\alpha$ in the
patch form close to Rankine vortices. We show that invariant tori survive when
the order $\alpha$ of the singular operator belongs to a Cantor set contained
in $(0,\frac12)$ with almost full Lebesgue measure. The proof is based on
several techniques from KAM theory, pseudo-differential calculus together with
Nash-Moser scheme in the spirit of the recent works
\cite{Baldi-Berti2018,Berti-Bolle15}. One key novelty here is a refined Egorov
type theorem established through a new approach based on the kernel dynamics
together with some hidden T\"opliz structures.
