As you mention the allusions between Tahei & Matashichi and R2-D2 & C-3PO seem to be the most obvious, but the way the film is cut/executed is also similar.
“The one thing I was really intrigued by was the fact that the story
was told from the two lowest characters. I decided that would be a
nice way to tell the Star Wars story…That was the strongest influence.
The fact that there was a princess trying to get through enemy lines
was more of a coincidence than anything else. In my film, the princess
is more of a stand-and-fight kind of princess. In the beginning, in
one of the first drafts, I did have a little bit more of her and a
Jedi, an older Jedi, trying to escape, but then it evolved into the
story of Luke.” - George Lucas
However, as the following Slashfilm article nicely explains, it seems the influence was stronger in previous drafts and with each update there were less and less influences in A New Hope.
It’s true that earlier versions of the Star Wars script featured a
Jedi Knight that was much more active and older in the story, more
like Toshiro Mifune’s General Makabe in The Hidden Fortress. In fact,
if you trace the lineage of drafts of the original Star Wars
screenplay and treatments, you can see that each revision took less
and less from Hidden Fortress, with the earliest versions bearing the
most resemblance to the film.
However that influence re-emerged as Lucas began to continue on in The Skywalker Saga, especially the prequels...
Perhaps the Star Wars film that embodies The Hidden Fortress the most,
though, is The Phantom Menace. When you compare the premise of the two
movies, the resemblance is much more striking than with A New Hope. A
wisened general (Mifune and Liam Neeson) works to escape enemy
territory in order to get a young princess (Misa Uehara and Natalie
Portman) to safety so that she might save her people. Along the way,
there are characters and situations that become reminiscent of The
Hidden Fortress, but the most direct influence would be in the use and
sacrifice of handmaidens.
This use of handmaidens as doubles that is prevalent on the surface of
The Hidden Fortress is echoed in The Phantom Menace with the use of
Sabe’s character (Keira Knightly) and the sacrifice of Princess Yuki’s
handmaiden is repeated in Attack of the Clones with Corde.
Although Padme is a “stand-and-fight” queen as much as her daughter
was as a princess, the story flourishes match between the prequels and
The Hidden Fortress are undeniable.
There are lots of videos made to show the parallels and influences: I will leave you with a few that Slashfilm also used as a point of reference, including one with George Lucas mentioning his Kurosawa influence, especially his visual influence.
