could I use else if(...........) in the template.
Yep:
{{#if x}}
  hello
{{else}}
  goodbye
{{/if}}
I want to check multiple with else if().....else if()......end
use another template in else part ? 
You can use standard Handlebars if/else syntax though often a better practice is to use a template helper but this depends on what you’re trying to achieve.
Meteor-jade supports else if branches:
if user.isAdmin
  h1 Hello admin
else if user.isConnected
  h1 Hello user
else
  h1 Hello visitor
which simply desugar to the same tests without the else if, ie:
if user.isAdmin
  h1 Hello admin
else
  if user.isConnected
    h1 Hello user
  else
    h1 Hello visitor
Thanks for all helping.
I should be use
if
else
     if
     else