I'm curious to know if research outputs as a PhD student count by the committee for promotion from assistant to associate professor only those produced during as assistant professor. I'll appreciate your input.
Only in the sense that you have a fuller CV. But most places, such as R1 universities in particular, will be looking a more recent work and evidence that such productivity is likely to continue. Old papers are less valuable for that.
At a teaching, rather than research, focused university or college the decision probably rests on other things than research, as well.
But a good CV ain't nothing. It is worth doing, and will help you get the assistant professor position in the first place.
Any work you have published will impact the total work product in your CV, so it is going to contribute to any job application you make. Works published as a PhD student are older, and in some cases they may even have accrued more citations ---by virtue of their age--- than later publications as an academic. In extreme cases someone might publish a groundbreaking paper during their PhD candidature. It is usual that all of your published works will be included on your CV and will therefore contribute to your total publication record.
As to applications for internal promotion, any sensible university will be guided to some degree by the prospects of the candidate getting a better offer at outside institutions, which will usually be affected by the total career work of the applicant. Some institutions may give greater weight to more recent work (mostly as a means of trying to infer how productive you will be post-promotion) but the promotion-decision will almost certainly still be affected by your total career work.