You can use an exclamation mark to capitalise a variable, like this:
$!{subject_pronoun}
will print as He
or She
or They
depending on what it’s been set to.
I’d recommend using a variable for pronouns over using multireplace because it removes the risk of typos and means you can edit it a lot more easily.
I made a pronoun template over here which may be helpful to take a look at: