When one posts a feature request here, is there any way to tell whether any responsible person has read it, i.e. a person responsible for developing new features?
The standard procedure to complete a feature-request is to add a mod-only status-tag status-declined, status-completed, status-deferred. This happens, as can be seen from inspecting the relevant tags, also on per-site metas from time to time. Other than that it can happen that CMs or other SE-staff comment on or answer such requests, implying that they saw the request.
There is, however, no separate "seen" feature, that indicates that somebody from SE has had a look; this might also not be very meaningful as information.
As long as there is no status tag applied the request can be considered as "alive" or "under consideration."
Requests on [meta.se] seem to get more attention than requests on per-site metas, and there one also has the possibility to place a bounty for extra visibility.