There's a reason I asked you whether you were using the beta in
this topic; Quite a few features have been added since the last release version(Gary is working on updating it, currently), including "Else If".
If you're doing numeric input, it makes more sense to isolate and use the number directly:
Set Text [CMD] to '{CMD}'
Quick Input, 'ytp volume {TXTNUM:CMD}'
You need to turn the "{CMD}" token into a variable because "{TXTNUM:}" doesn't support tokens(yet).
In the beta at least, you'll get a warning message, as "volume [1...100]" will add 100 different phrases to the speech engine.
If you're not using a large profile, or don't notice a difference in performance, this isn't an issue.
Otherwise, consider the granularity you need(E.G. [10;20;30;40;50;60;70;80;90;100], which only adds 10 commands).