You should be able to completely insert a round into the magazine tube through the loading gate,,and have the gate close behind it.
Then be able to insert another round into the magazine (if there's room of course) behind that first one by simply pushing in the loading gate with the tip of the bullet on the round in hand.

That last motion should push the round(s) already in the magazine tube slightly forward, allow the gate to be depressed fully and the new round to be inserted into the magazine.

This is the way the rifle/carbine was designed.
On the back side of the loading gate (I think the factory calls it the loading spring) is a rib that is tapered downward and towards the rear of the gate.
The rounds that are already inserted in the mag tube are pushed backwards by the mag spring and they sit just slightly behind the front edge of the gate itself but up against that tapered rib.
Upon pressing in on the loading gate, the round(s) are pushed forward by the taper of that small rib and the downward motion of the gate itself.
Now the gate is down and open,,the rounds in the magazine are held forward at the front edge of the gate,,and the next round can be inserted into the magazine.

The 94, 92, 86,,they all work the same.

The problem is with many of the post 64 and usually it's the late 70's and into the 80's production Model 94's.
Pre 64's will have the same issue also, but it's not as common as with post 64's
That gate does not fit correctly, better said that small tapered rib on it's backside is not the correct angle and usually is rough machined or cast is the usual problem on the post 64's.
Pre-64's can be just plain wear. Sometimes someone decides to reshape parts to make them work better and things like this result.
There's not a lot of difference in the part being good to go and one that doesn't work correctly

When pressing down on the gate, instead of smoothly moving the round(s) in the magazine forward and allowing you to simply insert another rd,,you get the gate not moving at all. You can't depress it, it won't open to allow a new round into the magazine.

As a result, many owners of post 64 94's have adopted a method of loading where they push a round 1/2 way into the gate and no more. Then the next one again 1/2 way,,ect. All this to keep the rounds in the magazine from backing up and letting the gate close.
'Cause once it's closed,,you can't get any more rounds into the mag.

It's not supposed to be that way,,was never designed to be that way,,but since so many Winchesters left the factory that way and people don't question it.

An older rifle might be plain old wear.

Take the loading gate out and inspect the back side. Usually you can reshape that rib and in the very least give it a good smoothing and polish.
Some will need a replacement if the originals are so badly formed or worn.
It must be able to cam the rounds in the magazine forward a small amt to allow the gate itself to be fully depressed.