Can I use `else if` over `elsif`?

You can use else if and it’s safe. However note that this means extra end keywords are needed.

if n == 1
  puts "foo"
elsif n == 2
  puts "bar"
end

is logically the same as:

if n == 1
  puts "foo"
else if n == 2
       puts "bar"
     end
end

or the equivalent:

if n == 1
  puts "foo"
else 
  if n == 2
    puts "bar"
  end
end