Move tabs in split screen

Yes.

To move a tab, touch the open tab that you want to move - and the instant that the tab “pops”, immediately drag the tab downwards to detach it from the tab bar; if the Action Menu appears, you paused a fraction too long before pulling downwards; just let-go - and tap safely elsewhere to dismiss the Action Menu.  

Once the tab is detached from the tab-bar, you can drag it to an alternate position on the tab bar - or to the tab bar of another Safari window - then release.

With “multi-touch” you can manipulate multiple tabs...

Multi-touch and Safari tabs

Whilst the tab is detached from the tab bar, as described above, you’ll notice that the tab has a green “+” badge together with an associated number; the number indicates the number of tabs being moved/manipulated by this action.

Whilst you maintain the original touch-gesture with your finger, you can use another finger to tap/add additional tabs from the tab bar to the selection; the green badge will increment the number for each additional selected tab, indicating the number of tabs within the stack.  Once selected, you can drag the stack to a new location as before.