I’m in love with the name [name_m]Victor[/name_m] for a baby boy. The only issue is my daughters middle name is [name_f]Victoria[/name_f]. Can I still name my son [name_m]Victor[/name_m]?
Yes, you can. No one will stop you.
I’d say as long as the other name in the combo is maybe something like [name_u]Grey[/name_u], [name_m]Grant[/name_m] or [name_m]Gabriel[/name_m] (to match your other daughter so she doesn’t feel left out) to go for it! If you love it, use it~
Unless you routinely call her by [name_f]Victoria[/name_f], I see no problem
It should be fine unless if your daughter wants to go by [name_f]Victoria[/name_f] in the future.
[name_m]Victor[/name_m] [name_u]Elliot[/name_u] 
[name_u]Elliot[/name_u] for gabri[name_f]ELLe[/name_f]
Knowing that your daughter’s middle name is [name_f]Victoria[/name_f] and your son’s name is [name_m]Victor[/name_m] would strike me as odd; it’s not terrible but it’s not something I personally would do. Most of the general population wouldn’t know this, so I think it’s probably okay. But please, please don’t incorporate your daughter’s first name into your son’s middle, that’s too much. If they’re going to have one repeating name, they deserve a different completely unique name to have a bit of their own identity… It’s cute to have matchy names when they’re little but they’re grown adults for much longer than they’re children. Anyway, I think it’s fine as long as your son’s middle name doesn’t contain part of your daughter’s first. Good luck! (Side note: an alternative to [name_m]Victor[/name_m] you might like is [name_m]Vincent[/name_m]! Have you thought about [name_m]Vincent[/name_m]?)