Yes it will reduce your cpu load. Its not at all easy to setup to record/stream your pc gaming though if your on the same pc..
I already am a casual live streamer and understand most of the settings. To be honest, my i3 does a pretty good job lol. For upgrades sake however (full PC upgrade), I am just trying to find out if there is actually any benefit to a capture card that will increase gaming performance while streaming. Its remarkable how CPU intensive it is, even for some of these higher end machines.