I think that for a Buddhist, the fact that something is recorded in the Pali canon is usually evidence enough that the Buddha said that -- its being in the canon is some of the only evidence that the Buddha ever said anything.
I mean, the fact that it's in the canon is usually evidence enough to assume it's true -- that is unless there's some other evidence to the contrary.
This answer references and summarises one example of what some "evidence to the contrary" might be:
- If something only appears in one sutta
- If it's in a sutta but not in the corresponding Agama
- If it doesn't seem to "fit" with other things (perhaps even other things in the same sutta)
So far as I know, none of this kind of reason or doubt is applicable to whether he talked about "psychic powers". This definition of iddhi cross-references dozens of suttas, from three of the Nikayas and from the Vinaya.
In summary I don't know any evidence that he didn't speak about it; it seems to me well-documented that he did.
For completeness, two other ways in which people sometimes dispute whether he said something are:
"Yes he said it but he contradicted or clarified that later" -- i.e. related to there being several turnings of the wheel, or the Buddha's using skilful means
But I doubt that this is applicable to whether he talked about psychic powers, I think that psychic powers appear in later canonical texts as well.
"Yes he said something like that but translators misunderstand or mistranslate it"
I think this is quite common, people may argue for example about what "rebirth" is and what the Buddha might really meant when he talked about that -- ditto other concepts like "world" and so on.
And that may be applicable here -- I think it may be up to you, your conscience, your teacher, a specific school of Buddhism, to decide how (and even whether) to interpret something like that -- answers to What are "Supernatural mental abilities" in relation to Buddhism? vary:
There is a belief among some practitioners of certain sects...
In my opinion, supernatural abilities are metaphors for various mental/psychological skills.
Of course they are real and not metaphors or vain myths.
My personal (perhaps inaccurate) summary or take-away of what he said about them is that they are not important; not required in order to be enlightened; not a proof of enlightenment; and something which monks are forbidden to show off to laypeople; that the Buddha himself had those powers and used them wisely (e.g. knowing other people's state of mind so that he'd know how and when to teach them); but perhaps not relevant, maybe a distraction or conceit or a cause of doubt, to other people, and perhaps best put aside (along with many other kinds of question which aren't helpful to the goal).