Time zone setting not reflected in timestamp

Epoch timestamps are always Coordinated Universal Time (UTC), so as such are timezone independent, and there is no need (point) to specify a timezone parameter.

For the second example if `eventtime1` were in that format, that would be a suitable use of the timezone parameter:

date {
  match => ["logtime", "yyyy-MM-dd HH:mm:ss"]
  timezone => "America/New_York"
  on_error => "no_match"
}

date {
 match => ["logtime", "yyyy-MM-dd HH:mm:ss"]
 timezone => "America/New_York"
 on_error => "no_match"
}

Thank you for your reply.
Let me explain the issue in more detail.

The following eventtime exists in the log:
eventtime= [removed by moderator] 518829

The following extracts the first 10 characters as eventtime1, and by default it is extracted in UNIX time.
-----------
if [eventtime] != "" {
#reduce epoch time from microseconds
grok {
match => {
"eventtime" => [
"(?P<eventtime1>\\d{10}).*"
]
}
on_error => "not_eventtime1"
}
if ![not_eventtime1] {
date {
match => ["eventtime1", "UNIX", "UNIX_MS"]
on_error => "not_eventtime1_valid"
}
}
-----------

Replacing the date{} part with the following will display the current UTC time as the timestamp instead of the eventtime time.
date {
match => ["eventtime1", "yyyy-MM-dd HH:mm:ss"]
on_error => "not_eventtime1_valid"
}