It's an autowin if you hold but Terran all ins are really strong and diverse.
If my scv scout gets there after their wall is finished, I don't know if it's seven rax marine, marine/tank/banshee, mass reaper chaos, Thor/marine/autorepair scvs. Even after a perfect scan, they can be very hard to defend.
I've gotta learn some cheesy builds. That BC cheese sound weak.
in tvt, when i'm going 1 rax expo, i generally built a single rine, then cut rine production to get tanks with siege out asap, then resume rines.
generally this isn't a huge delay, but after i start my CC, my #1 priority is getting double geyser down so i can beeline to siege tanks.
by building a single rine, this lets me get my CC down a little faster, which lets me get my geysers down a little faster. then i'll resume rines. siege pretty much stops any ground based all in.
dropping a scan can generally give you a clue if you are going to see an air component to the all in. If you do see banshees, a fast start on the gas/factory still helps as you can get a port down for vikes.