Is there anyway where we can use if/else concept in feature file? For example:
Scenario: User should be able to check login page
Given I am on login pag
Not that I am aware of. Gherkin (and cucumber) are best used when they specify discreet business cases though, and should be repeatable, else they get hard to follow and test. It looks like you have two stories here at least:
Scenario: A new user should be asked to sign in
Given I am a new user
And I navigate to the login page
When I click on SignIn button
I should not be able to get to the home page
Scenario: An existing user should be able to log in
Given I am an existing user
And I navigate to the login page
And I submit valid credentials
When I click on SignIn button
I should be taken to the home page