The definition of dictatorial government is either a single person or a small group of people. So there being three branches of government doesn't necessarily prohibit a government from being a dictatorship if they are all working together to enact their authoritarian control without constitutional limits.
But really this is just pointless semantics. It doesn't matter what it is called it is still a problem.
Two of them jump at the command one the other one, one out of fear (because he has ended the careers of every rep that has crossed him), and the other has been packed with life-time-appointment sycophants who put loyalty to the cut over anything else.
Russia (or literally any other dictatorial tyre pyre) also has three branches of government and a token opposition, for all the good it does.
Just because you have a nice piece of paper that outlines some kind of de jure separation of powers, doesn't mean shit in practice. Russia (and prior to it, the USSR) has no shortage of such pieces of paper.
The Supreme Court has repeatedly and crassly decided in favor of the current administration; among their decisions one to elevate the president above the law, and a carte Blanche for gerrymandering with a footnote that that is against the spirit of democracy.
The congress is dominated by the republicans, who have given up on every last shred of dignity and turned themselves into yes men that will approve anything Trump says, from a justified invasion of Greenland to how unnecessary it would be to publish the Epstein files.
And the executive branch currently hunts down government employees with an unsuitable personal opinion, takes jet plane bribes from foreign leaders, and tries to eradicate slavery and the Native American genocide from museums and school books.
Tell me about those three branches again. Right now, they have been perverted into a single tool to carry out the whims of an egotistic asshole backed by a powerful group of conservative activists.
But really this is just pointless semantics. It doesn't matter what it is called it is still a problem.