。
It's fair to say she has a sweet tooth.
Literal
She [topic-は] sweet things [target-に] eyes [subject-が]-not [quotative-と] saying-ok [probably-でしょう].
Three layers of hedge stack here. 目がない ('have no eye for' = 'be crazy about / can't resist') is itself an idiom: literally 'no eye exists,' figuratively 'one has weakness for / can't say no to.' Then ~といっていい ('it's fine to say that') is a comment on the strength of the claim — 'this characterization is appropriate.' Then ~でしょう adds polite conjecture, softening it to 'I'd say.' The cascade lets the speaker make a strong claim while still leaving room for disagreement — Japanese strongly prefers this kind of indirect framing for personal observations about others.